diff --git a/.commandcode/taste/frontend/taste.md b/.commandcode/taste/frontend/taste.md
index b414b0ab..335bc638 100644
--- a/.commandcode/taste/frontend/taste.md
+++ b/.commandcode/taste/frontend/taste.md
@@ -11,3 +11,8 @@
 - z-index must always be controlled through semantic variables (named layer roles, e.g. column-local layers vs overlay layers with stacking-context audit notes), never bare numeric literals. Confidence: 0.95
 - Cares that finished styling modules (e.g. the `.tc-prose` typography module) are reusable in other Tailwind projects — asked about cross-project portability before confirming: values self-contained, zero-runtime, purely CSS-variable-driven forms (vendor copy → npm package → Tailwind `@plugin`) over build-tool-coupled ones (Sass mixins would become dead code once copied out). Confidence: 0.65
 - Styling-refactor acceptance runs on two tracks that must never be mixed: value-preserving steps (token renames, same-value re-pointing like `#b07d2e` → `--tc-depth-2`, deleting dead fallbacks) must prove computed-style equivalence (grep zero-hit lists + build-output comparison), while any value-altering fix (e.g. re-targeting the unsaved-state gold to depth-1) is logged as a registered visual change and moved to the screenshot-baseline track — ambiguous historical intent gets logged as a decision, never silently fixed. Confidence: 0.7
+- For fallible user-input flows such as attachment uploads, prefers graceful recovery over pretending errors can be eliminated: show failures explicitly, preserve the user's input, and let them remove or retry it. Confidence: 0.9
+- Expects attachment inputs to support common plaintext and source-code extensions (including Markdown and JavaScript) rather than limiting acceptance to files the browser labels `text/plain`. Confidence: 0.9
+- In chat message bubbles, wants image previews width-constrained so they do not stretch the bubble, and wants non-image files represented as visible attachment cards rather than bare links or omitted UI. Confidence: 0.9
+- Wants user-facing UI copy stripped of development-process text, implementation details, and engineering jargon; labels, states, and errors should be phrased around what ordinary users need to understand and do. Confidence: 0.95
+- For pasted or voice-transcribed text, prefers a character-count-based hybrid UX: shorter content should be inserted directly into the composer rather than uploaded and shown as an attachment, while genuinely long content can remain an attachment. Confidence: 0.9
diff --git a/.commandcode/taste/taste.md b/.commandcode/taste/taste.md
index 57d8fa07..f279d953 100644
--- a/.commandcode/taste/taste.md
+++ b/.commandcode/taste/taste.md
@@ -2,5 +2,6 @@
 
 ## Communication
 - Communicates in Simplified Chinese; respond in Chinese. Confidence: 0.7
+- For project handoffs/status recaps, prefers a concise, immediately reusable summary structured as: brief requirement context, completed work, and remaining work. Confidence: 0.9
 - When asked to react to external reviews (e.g. a GPT critique of its own spec artifacts), first fact-checks the review's claims against the codebase, then delivers a structured verdict — verified-valid points, points held with reservations, plus findings the review missed — and proposes concrete revisions instead of blindly accepting or dismissing. Confidence: 0.8
 - Also commissions adversarial re-audits of the assistant's own recent replies, via a second model ("@codex 你来阅读下这最近2条回复看下是否有不对的地方") — so every factual/numeric claim written into replies or artifacts may be re-checked later; on such an audit pass, re-verify each claim against the code (grep counts, file:line evidence, exact numbers not approximations), report findings classified by severity (substantive error vs inconsistency/omission), own mistakes plainly, propose concrete fixes to the artifacts, and apply corrections only after confirmation. Confidence: 0.75
diff --git a/.commandcode/taste/workflow/taste.md b/.commandcode/taste/workflow/taste.md
index 6b79e112..219777fa 100644
--- a/.commandcode/taste/workflow/taste.md
+++ b/.commandcode/taste/workflow/taste.md
@@ -5,3 +5,9 @@
 - Operates as a principles-then-review loop: states a few inviolable principles up front, delegates the remaining design judgment ("其他的你再看看"), and then wants the written/revised artifacts summarized and presented for his explicit confirmation before implementation/apply begins ("给我再看一眼变更，我来确认") — end the authoring phase by waiting, don't proceed into apply unbidden. Confidence: 0.85
 - When confirming a design before apply, wants concrete end-state previews — the finished module's form factor, the planned directory/file structure (e.g. the `tokens/` tree), and sample code — not prose summaries alone ("可以先把 tokens 的结构给我看吗"). Confidence: 0.7
 - When a batch of edits lands on the same artifact in parallel, don't trust the per-edit result snapshots (they can show stale/inconsistent state) — re-verify the file's final on-disk state (grep for each inserted marker/phrase, spot-read the long lines) before running validation or reporting completion; caught this twice (design.md, tasks.md) and corrected course. Confidence: 0.65
+- For a small PR that is only one slice of a larger initiative, create a long-lived tracking Issue that records the original roadmap, current completed/uncompleted status, and ongoing effectiveness follow-up; link the PR as a phase without closing the umbrella Issue. Confidence: 0.9
+- Allows project `.commandcode` configuration and Taste preference files to be committed to the Git repository rather than kept local-only. Confidence: 1.0
+- Once implementation is accepted, expects the assistant to complete the delivery workflow by committing and pushing the code, then synchronizing the PR description and tracking Issue rather than stopping at local changes. Confidence: 0.8
+- Before extracting helpers, modules, or hooks during a simplification refactor, first assess whether the abstraction is actually necessary; avoid merely relocating complexity, and prefer the smallest local extraction only when concrete repetition or maintenance risk justifies it. Confidence: 0.85
+- Dislikes crowded catch-all directories and leans toward grouping cohesive domain logic into a dedicated subdirectory when several related files accumulate. Confidence: 0.7
+- For a proposed module/directory migration, wants a clear necessity judgment first; if it is warranted, prefers completing the full migration and reference updates in one pass rather than splitting it into partial follow-ups. Confidence: 0.8
diff --git a/app/api/attachments/[id]/content/route.ts b/app/api/attachments/[id]/content/route.ts
new file mode 100644
index 00000000..23d3fbf1
--- /dev/null
+++ b/app/api/attachments/[id]/content/route.ts
@@ -0,0 +1,60 @@
+import { and, eq } from "drizzle-orm"
+import { getCurrentUserId } from "@/lib/auth/server"
+import { db } from "@/lib/db"
+import { attachments } from "@/lib/db/schema"
+import { getObjectBytes, isR2Configured } from "@/lib/storage/r2"
+
+type RouteContext = { params: Promise<{ id: string }> }
+
+export async function GET(_req: Request, { params }: RouteContext) {
+  const userId = await getCurrentUserId()
+  if (!userId) return Response.json({ error: "未登录" }, { status: 401 })
+  if (!isR2Configured()) {
+    return Response.json({ error: "文件服务暂不可用" }, { status: 503 })
+  }
+
+  const { id } = await params
+  const [row] = await db
+    .select()
+    .from(attachments)
+    .where(and(eq(attachments.id, id), eq(attachments.userId, userId)))
+    .limit(1)
+
+  if (!row) return Response.json({ error: "附件不存在" }, { status: 404 })
+  if (row.status !== "ready") {
+    return Response.json(
+      {
+        error:
+          row.status === "failed"
+            ? "这个文件暂时无法预览"
+            : "文件尚未准备好",
+      },
+      { status: row.status === "failed" ? 422 : 409 }
+    )
+  }
+  if (row.mimeType !== "text/plain") {
+    return Response.json({ error: "暂不支持预览这个文件" }, { status: 415 })
+  }
+
+  let bytes: Uint8Array
+  try {
+    bytes = await getObjectBytes(row.key)
+  } catch {
+    return Response.json({ error: "文件读取失败，请稍后重试" }, { status: 502 })
+  }
+
+  let content: string
+  try {
+    content = new TextDecoder("utf-8", { fatal: true }).decode(bytes)
+  } catch {
+    return Response.json({ error: "这个文件暂时无法预览" }, { status: 422 })
+  }
+
+  return new Response(content, {
+    headers: {
+      "Cache-Control": "private, no-store",
+      "Content-Type": "text/plain; charset=utf-8",
+      "X-Content-Type-Options": "nosniff",
+    },
+  })
+}
diff --git a/app/api/attachments/[id]/ingest/route.ts b/app/api/attachments/[id]/ingest/route.ts
index c2c1f5d1..68d3cbe9 100644
--- a/app/api/attachments/[id]/ingest/route.ts
+++ b/app/api/attachments/[id]/ingest/route.ts
@@ -113,7 +113,17 @@ export async function POST(_req: Request, { params }: RouteContext) {
     return Response.json({ status: "ready", pageCount: extraction.pageCount })
   }
 
-  // 非 PDF 类型：仅确认对象存在即就绪（图片/压缩包/视频一期只存储、不解析内容）
+  if (row.mimeType === "text/plain") {
+    try {
+      new TextDecoder("utf-8", { fatal: true }).decode(
+        await getObjectBytes(row.key)
+      )
+    } catch {
+      return markFailed(userId, id, row.key, "文件内容不是有效的 UTF-8 文本")
+    }
+  }
+
+  // 其他非 PDF 类型：仅确认对象存在即就绪（图片/压缩包/视频一期只存储、不解析内容）
   await db
     .update(attachments)
     .set({ status: "ready", size: actualSize })
diff --git a/app/api/attachments/[id]/route.ts b/app/api/attachments/[id]/route.ts
index 49a0c8ef..084c755f 100644
--- a/app/api/attachments/[id]/route.ts
+++ b/app/api/attachments/[id]/route.ts
@@ -10,7 +10,7 @@ type RouteContext = { params: Promise<{ id: string }> }
  * 附件的稳定读取入口：302 到短时效 presigned GET。
  * 消息 parts 里持久化的是本路由的相对路径，presigned URL 每次请求现签，天然不过期。
  */
-export async function GET(_req: Request, { params }: RouteContext) {
+export async function GET(req: Request, { params }: RouteContext) {
   const userId = await getCurrentUserId()
   if (!userId) return Response.json({ error: "未登录" }, { status: 401 })
   if (!isR2Configured()) {
@@ -24,7 +24,11 @@ export async function GET(_req: Request, { params }: RouteContext) {
     .limit(1)
   if (!row) return Response.json({ error: "附件不存在" }, { status: 404 })
 
-  return Response.redirect(await presignDownload(row.key), 302)
+  const download = new URL(req.url).searchParams.get("download") === "1"
+  return Response.redirect(
+    await presignDownload(row.key, download ? row.filename : undefined),
+    302
+  )
 }
 
 /** composer 里移除附件时清理 R2 对象与 DB 行 */
diff --git a/app/thread-chat/branching/branchable-chat.tsx b/app/thread-chat/branching/branchable-chat.tsx
index 3ca6d509..dc984a75 100644
--- a/app/thread-chat/branching/branchable-chat.tsx
+++ b/app/thread-chat/branching/branchable-chat.tsx
@@ -25,6 +25,7 @@ import { MessageArtifacts } from "../orchestration/artifacts/message-artifacts"
 import { AnchoredAssistantBody } from "./assistant/anchored-assistant-body"
 import type { MessageActionViewState } from "../chat/actions/message-action-types"
 import type { ThreadMessageActionCommands } from "../chat/actions/message-action-commands"
+import type { CommandFileReference } from "../net/commands/conversation-commands"
 
 export interface BranchableChatProps {
   state: ThreadTreeState
@@ -55,7 +56,7 @@ export interface BranchableChatProps {
   composerPrefill?: string
   /** 根 Thread 模型切换意图；分支 selector 仍由本层锁定。 */
   onModelChange: (modelId: string) => void
-  onSend: (text: string) => void
+  onSend: (text: string, files: CommandFileReference[]) => void
   messageActionState?: MessageActionViewState
   messageCommands?: ThreadMessageActionCommands
 }
diff --git a/app/thread-chat/chat/chat-view.tsx b/app/thread-chat/chat/chat-view.tsx
index ec43dfce..e3b13812 100644
--- a/app/thread-chat/chat/chat-view.tsx
+++ b/app/thread-chat/chat/chat-view.tsx
@@ -17,6 +17,7 @@ import { ConversationComposer } from "./composer/conversation-composer"
 import { ConversationMessage } from "./message/conversation-message"
 import type { MessageActionViewState } from "./actions/message-action-types"
 import type { ThreadMessageActionCommands } from "./actions/message-action-commands"
+import type { CommandFileReference } from "../net/commands/conversation-commands"
 
 export interface ChatViewProps {
   /** 会话 id：写到 .msg-list 的 data-list 上（划选气泡靠它反查消息） */
@@ -48,7 +49,7 @@ export interface ChatViewProps {
   /** 分支锁定时显示模型切换限制说明；生成期间仅禁用。 */
   modelSelectorDisabledReason?: "branch" | "busy"
   onModelChange: (modelId: string) => void
-  onSend: (text: string) => void
+  onSend: (text: string, files: CommandFileReference[]) => void
   messageActionState?: MessageActionViewState
   messageCommands?: ThreadMessageActionCommands
   editableUserMessageId?: string
diff --git a/app/thread-chat/chat/composer/conversation-composer.tsx b/app/thread-chat/chat/composer/conversation-composer.tsx
index 38c5fb42..156666d9 100644
--- a/app/thread-chat/chat/composer/conversation-composer.tsx
+++ b/app/thread-chat/chat/composer/conversation-composer.tsx
@@ -1,12 +1,56 @@
 "use client"
 
-import React, { useEffect, useRef } from "react"
+import React, {
+  useCallback,
+  useEffect,
+  useRef,
+  useState,
+  type ChangeEvent,
+  type ClipboardEvent,
+  type DragEvent,
+} from "react"
+import { FileIcon, PlusIcon, XIcon } from "lucide-react"
+import { toast } from "sonner"
+import {
+  IMAGE_ATTACHMENT_LIMITS,
+  IMAGE_MODEL_VALIDATION_MESSAGE,
+} from "@/constants/attachment"
 import { ThreadModelSelector } from "./thread-model-selector"
 import {
   composerMaxHeight,
   composerSubmission,
   shouldSubmitComposerKey,
 } from "./conversation-composer-logic"
+import {
+  canAddThreadImages,
+  canSendThreadAttachments,
+  createPastedTextFile,
+  hasUnsupportedReadyImages,
+  isThreadComposerFile,
+  isThreadComposerImageFile,
+  readyThreadAttachmentReferences,
+  shouldInlinePastedText,
+  THREAD_COMPOSER_ACCEPT,
+  type ThreadComposerAttachment,
+} from "./thread-attachment-model"
+import {
+  deleteUploadedAttachment,
+  normalizeAttachmentFile,
+  uploadAttachment,
+  validateAttachmentFile,
+  type UploadedAttachmentReference,
+} from "@/lib/attachments/upload"
+import { preprocessImageAttachment } from "@/lib/attachments/image"
+import {
+  Attachment,
+  AttachmentAction,
+  AttachmentActions,
+  AttachmentContent,
+  AttachmentDescription,
+  AttachmentGroup,
+  AttachmentMedia,
+  AttachmentTitle,
+} from "@/components/ui/attachment"
 
 type ConversationComposerProps = {
   variant: "column" | "canvas"
@@ -18,7 +62,7 @@ type ConversationComposerProps = {
   modelSelectorDisabled: boolean
   modelSelectorDisabledReason?: "branch" | "busy"
   onModelChange?(modelId: string): void
-  onSend?(text: string): void
+  onSend?(text: string, files: UploadedAttachmentReference[]): void
   onStop?(): void
   onBeforeSend?(): void
 }
@@ -28,6 +72,10 @@ function autoGrow(ta: HTMLTextAreaElement, maxHeight: number) {
   ta.style.height = Math.min(ta.scrollHeight, maxHeight) + "px"
 }
 
+function hasDraggedFiles(event: DragEvent<HTMLElement>) {
+  return Array.from(event.dataTransfer.types).includes("Files")
+}
+
 export function ConversationComposer({
   variant,
   threadId,
@@ -43,6 +91,10 @@ export function ConversationComposer({
   onBeforeSend,
 }: ConversationComposerProps) {
   const taRef = useRef<HTMLTextAreaElement | null>(null)
+  const fileInputRef = useRef<HTMLInputElement | null>(null)
+  const dragDepthRef = useRef(0)
+  const [attachments, setAttachments] = useState<ThreadComposerAttachment[]>([])
+  const [isDragging, setIsDragging] = useState(false)
   const canvas = variant === "canvas"
   const maxHeight = composerMaxHeight(variant)
 
@@ -50,14 +102,154 @@ export function ConversationComposer({
     const ta = taRef.current
     if (!ta || !onSend) return
     const text = composerSubmission(ta.value, busy)
-    if (!text) return
+    if (!text || !canSendThreadAttachments(attachments)) return
+    if (hasUnsupportedReadyImages(modelId, attachments)) {
+      toast.error(IMAGE_MODEL_VALIDATION_MESSAGE)
+      return
+    }
     ta.value = ""
     ta.style.height = "auto"
     onBeforeSend?.()
-    onSend(text)
+    onSend(text, readyThreadAttachmentReferences(attachments))
+    if (!canvas) setAttachments([])
     ta.focus(canvas ? { preventScroll: true } : undefined)
   }
 
+  const appendFiles = useCallback(
+    (files: Iterable<File>) => {
+      const updateAttachment = (
+        id: string,
+        patch: Partial<Omit<ThreadComposerAttachment, "id">>
+      ) =>
+        setAttachments((current) =>
+          current.map((attachment) =>
+            attachment.id === id ? { ...attachment, ...patch } : attachment
+          )
+        )
+
+      const incoming = Array.from(files)
+      const incomingImageCount = incoming.filter(
+        isThreadComposerImageFile
+      ).length
+      if (!canAddThreadImages(attachments, incomingImageCount)) {
+        toast.error(
+          `单次最多添加 ${IMAGE_ATTACHMENT_LIMITS.maxFilesPerMessage} 张图片`
+        )
+        return
+      }
+
+      for (const sourceFile of incoming) {
+        const id = crypto.randomUUID()
+        const file = normalizeAttachmentFile(sourceFile)
+        try {
+          if (!isThreadComposerFile(file)) {
+            throw new Error(`不支持的文件类型：${file.type || "未知"}`)
+          }
+          validateAttachmentFile(file)
+        } catch (error) {
+          setAttachments((current) => [
+            ...current,
+            {
+              id,
+              file,
+              status: "error",
+              progress: 0,
+              error: error instanceof Error ? error.message : "附件校验失败",
+            },
+          ])
+          continue
+        }
+        setAttachments((current) => [
+          ...current,
+          { id, file, status: "uploading", progress: 0 },
+        ])
+        void preprocessImageAttachment(file)
+          .then((file) => {
+            validateAttachmentFile(file)
+            updateAttachment(id, { file })
+            return uploadAttachment(file, {
+              onProgress(progress) {
+                updateAttachment(id, { progress })
+              },
+            }).then((result) => ({ file, result }))
+          })
+          .then(({ file, result }) =>
+            updateAttachment(id, {
+              file,
+              status: "ready",
+              progress: 1,
+              serverId: result.serverId,
+              reference: result.reference,
+            })
+          )
+          .catch((error) =>
+            updateAttachment(id, {
+              status: "error",
+              error:
+                error instanceof Error ? error.message : "附件上传失败",
+            })
+          )
+      }
+    },
+    [attachments]
+  )
+
+  const handleFileChange = (event: ChangeEvent<HTMLInputElement>) => {
+    appendFiles(event.currentTarget.files ?? [])
+    event.currentTarget.value = ""
+  }
+
+  const handleDragEnter = (event: DragEvent<HTMLDivElement>) => {
+    if (!hasDraggedFiles(event)) return
+    event.preventDefault()
+    dragDepthRef.current += 1
+    setIsDragging(true)
+  }
+
+  const handleDragOver = (event: DragEvent<HTMLDivElement>) => {
+    event.preventDefault()
+    if (hasDraggedFiles(event)) event.dataTransfer.dropEffect = "copy"
+  }
+
+  const handleDragLeave = (event: DragEvent<HTMLDivElement>) => {
+    event.preventDefault()
+    dragDepthRef.current = Math.max(0, dragDepthRef.current - 1)
+    if (dragDepthRef.current === 0) setIsDragging(false)
+  }
+
+  const handleDrop = (event: DragEvent<HTMLDivElement>) => {
+    event.preventDefault()
+    dragDepthRef.current = 0
+    setIsDragging(false)
+    appendFiles(event.dataTransfer.files)
+  }
+
+  const handlePaste = (event: ClipboardEvent<HTMLDivElement>) => {
+    const pastedFiles = Array.from(event.clipboardData.items)
+      .filter((item) => item.kind === "file")
+      .map((item) => item.getAsFile())
+      .filter((file): file is File => file !== null)
+    if (pastedFiles.length > 0) {
+      event.preventDefault()
+      appendFiles(pastedFiles)
+      return
+    }
+    const text = event.clipboardData.getData("text/plain")
+    if (!text) return
+    if (shouldInlinePastedText(text)) {
+      const ta = taRef.current
+      if (!ta) return
+      event.preventDefault()
+      const start = ta.selectionStart
+      const end = ta.selectionEnd
+      ta.setRangeText(text, start, end, "end")
+      autoGrow(ta, maxHeight)
+      return
+    }
+    event.preventDefault()
+    appendFiles([createPastedTextFile(text)])
+  }
+
   useEffect(() => {
     const ta = taRef.current
     if (!ta || !prefill || ta.value !== "") return
@@ -67,6 +259,21 @@ export function ConversationComposer({
     ta.setSelectionRange(ta.value.length, ta.value.length)
   }, [canvas, maxHeight, threadId, prefill])
 
+  const handleBoxPointerDown = (event: React.MouseEvent<HTMLDivElement>) => {
+    // 点击 box 任意位置都把焦点交给 textarea（附件卡片的交互不吞掉这个行为之外的事）。
+    if (event.target instanceof Element && event.target.closest("button, a")) {
+      if (event.target.closest('[data-slot="attachment"]')) return
+    }
+    const ta = taRef.current
+    if (!ta) return
+    const isFocused = document.activeElement === ta
+    const selection = window.getSelection()
+    if (isFocused || !selection?.isCollapsed) return
+    event.preventDefault()
+    ta.focus()
+    ta.setSelectionRange(ta.value.length, ta.value.length)
+  }
+
   const textarea = (
     <textarea
       ref={taRef}
@@ -110,12 +317,93 @@ export function ConversationComposer({
     />
   ) : null
 
-  const promptStack = (
-    <div className={canvas ? "cv-prompt-stack" : "prompt-stack"}>
-      {canvas ? selector : textarea}
-      {canvas ? textarea : selector}
+  const attachmentTray =
+    !canvas && attachments.length > 0 ? (
+      <AttachmentGroup
+        data-testid="composer-attachment-tray"
+        aria-label="已添加的附件"
+        className="composer-attachment-tray w-full max-w-full"
+      >
+        {attachments.map((attachment) => (
+          <Attachment
+            key={attachment.id}
+            data-testid="composer-attachment-item"
+            className="composer-attachment-item w-60 max-w-[min(15rem,80vw)] flex-nowrap"
+            size="sm"
+          >
+            <AttachmentMedia aria-hidden="true">
+              <FileIcon />
+            </AttachmentMedia>
+            <AttachmentContent className="overflow-hidden">
+              <AttachmentTitle>
+                {attachment.file.name || "未命名附件"}
+              </AttachmentTitle>
+              <AttachmentDescription>
+                {attachment.status === "uploading"
+                  ? `上传中 ${Math.round(attachment.progress * 100)}%`
+                  : attachment.status === "ready"
+                    ? "已就绪"
+                    : attachment.error ?? "上传失败"}
+              </AttachmentDescription>
+            </AttachmentContent>
+            <AttachmentActions>
+              <AttachmentAction
+                type="button"
+                aria-label={`移除 ${attachment.file.name || "未命名附件"}`}
+                data-testid="composer-remove-attachment"
+                onClick={(event) => {
+                  event.stopPropagation()
+                  setAttachments((current) =>
+                    current.filter((item) => item.id !== attachment.id)
+                  )
+                  if (attachment.serverId) {
+                    void deleteUploadedAttachment(attachment.serverId)
+                  }
+                }}
+              >
+                <XIcon />
+              </AttachmentAction>
+            </AttachmentActions>
+          </Attachment>
+        ))}
+      </AttachmentGroup>
+    ) : null
+
+  const promptStack = canvas ? (
+    <div className="cv-prompt-stack">
+      {selector}
+      {textarea}
+    </div>
+  ) : (
+    <div className="prompt-stack">
+      {attachmentTray}
+      {textarea}
+      <div className="composer-tools">
+        <input
+          ref={fileInputRef}
+          data-testid="composer-file-input"
+          className="sr-only"
+          type="file"
+          multiple
+          accept={THREAD_COMPOSER_ACCEPT}
+          tabIndex={-1}
+          onChange={handleFileChange}
+        />
+        <button
+          type="button"
+          className="attach-btn"
+          aria-label="添加附件"
+          title="添加附件"
+          data-testid="composer-attach-button"
+          onClick={() => fileInputRef.current?.click()}
+        >
+          <PlusIcon size={14} aria-hidden="true" />
+        </button>
+        {selector}
+      </div>
     </div>
   )
+
   const button = busy ? (
     <button
       className={canvas ? "cv-send stop" : "send stop"}
@@ -125,7 +413,11 @@ export function ConversationComposer({
       停止
     </button>
   ) : (
-    <button className={canvas ? "cv-send" : "send"} onClick={doSend}>
+    <button
+      className={canvas ? "cv-send" : "send"}
+      onClick={doSend}
+      disabled={!canvas && !canSendThreadAttachments(attachments)}
+    >
       发送
     </button>
   )
@@ -141,7 +433,15 @@ export function ConversationComposer({
   return (
     <div className={`composer ${isMain ? "" : "branch"}`}>
       <div className="lane">
-        <div className="box">
+        <div
+          className={`box${isDragging ? " attach-dragging" : ""}`}
+          onDragEnter={handleDragEnter}
+          onDragOver={handleDragOver}
+          onDragLeave={handleDragLeave}
+          onDrop={handleDrop}
+          onPaste={handlePaste}
+          onMouseDown={handleBoxPointerDown}
+        >
           {promptStack}
           {button}
         </div>
diff --git a/app/thread-chat/chat/composer/thread-attachment-model.ts b/app/thread-chat/chat/composer/thread-attachment-model.ts
new file mode 100644
index 00000000..58a6b2ad
--- /dev/null
+++ b/app/thread-chat/chat/composer/thread-attachment-model.ts
@@ -0,0 +1,97 @@
+import {
+  IMAGE_ATTACHMENT_MIME_TYPES,
+  IMAGE_ATTACHMENT_LIMITS,
+  INLINE_PASTED_TEXT_CHAR_LIMIT,
+  TEXT_ATTACHMENT_FILE_EXTENSIONS,
+} from "@/constants/attachment"
+import { supportsModelImageInput } from "@/constants/model"
+import {
+  isTextAttachmentFile,
+  type UploadedAttachmentReference,
+} from "@/lib/attachments/upload"
+
+export const THREAD_COMPOSER_MIME_TYPES = [
+  "text/plain",
+  ...IMAGE_ATTACHMENT_MIME_TYPES,
+] as const
+
+export const THREAD_COMPOSER_ACCEPT = [
+  ...THREAD_COMPOSER_MIME_TYPES,
+  ...TEXT_ATTACHMENT_FILE_EXTENSIONS,
+].join(",")
+
+export function isThreadComposerImageFile(
+  file: Pick<File, "type">
+): boolean {
+  return (IMAGE_ATTACHMENT_MIME_TYPES as readonly string[]).includes(file.type)
+}
+
+export function isThreadComposerFile(file: File): boolean {
+  return isTextAttachmentFile(file) || isThreadComposerImageFile(file)
+}
+
+export type ThreadComposerAttachmentStatus = "uploading" | "ready" | "error"
+
+export interface ThreadComposerAttachment {
+  id: string
+  file: File
+  status: ThreadComposerAttachmentStatus
+  progress: number
+  error?: string
+  serverId?: string
+  reference?: UploadedAttachmentReference
+}
+
+export function shouldInlinePastedText(text: string): boolean {
+  return text.length <= INLINE_PASTED_TEXT_CHAR_LIMIT
+}
+
+export function createPastedTextFile(
+  text: string,
+  now: number = Date.now()
+): File {
+  return new File([text], `pasted-text-${now}.txt`, {
+    type: "text/plain",
+  })
+}
+
+export function canAddThreadImages(
+  attachments: readonly ThreadComposerAttachment[],
+  incomingCount: number
+): boolean {
+  const currentCount = attachments.filter((attachment) =>
+    isThreadComposerImageFile(attachment.file)
+  ).length
+  return (
+    currentCount + incomingCount <=
+    IMAGE_ATTACHMENT_LIMITS.maxFilesPerMessage
+  )
+}
+
+export function canSendThreadAttachments(
+  attachments: readonly ThreadComposerAttachment[]
+): boolean {
+  return attachments.every((attachment) => attachment.status === "ready")
+}
+
+export function readyThreadAttachmentReferences(
+  attachments: readonly ThreadComposerAttachment[]
+): UploadedAttachmentReference[] {
+  return attachments.flatMap((attachment) =>
+    attachment.status === "ready" && attachment.reference
+      ? [attachment.reference]
+      : []
+  )
+}
+
+export function hasUnsupportedReadyImages(
+  modelId: string | undefined,
+  attachments: readonly ThreadComposerAttachment[]
+): boolean {
+  return (
+    !supportsModelImageInput(modelId) &&
+    readyThreadAttachmentReferences(attachments).some((file) =>
+      file.mediaType.startsWith("image/")
+    )
+  )
+}
diff --git a/app/thread-chat/chat/composer/thread-model-selector.tsx b/app/thread-chat/chat/composer/thread-model-selector.tsx
index d74ce438..ab5aae9e 100644
--- a/app/thread-chat/chat/composer/thread-model-selector.tsx
+++ b/app/thread-chat/chat/composer/thread-model-selector.tsx
@@ -105,7 +105,7 @@ export function ThreadModelSelector({
       variant="ghost"
       size="sm"
       disabled={disabled}
-      className={`thread-model-selector${compact ? "compact" : ""}${isBranchLocked ? "branch-locked" : ""}`}
+      className={`thread-model-selector${compact ? " compact" : ""}${isBranchLocked ? " branch-locked" : ""}`}
     >
       {compact ? <Bot aria-hidden="true" size={12} /> : undefined}
     </ModelSelector.Trigger>
diff --git a/app/thread-chat/chat/message/conversation-message.tsx b/app/thread-chat/chat/message/conversation-message.tsx
index ce9d8d42..738cd2db 100644
--- a/app/thread-chat/chat/message/conversation-message.tsx
+++ b/app/thread-chat/chat/message/conversation-message.tsx
@@ -10,6 +10,7 @@ import type { ThreadMessageActionCommands } from "../actions/message-action-comm
 import { AssistantMessageToolbar } from "../actions/assistant-message-toolbar"
 import { assistantMessagePresentation } from "./conversation-message-logic"
 import { EditableUserMessage } from "./editable-user-message"
+import { UIMessageSupplementalParts } from "./ui-message-parts"
 import {
   hasCompletedAssistantActions,
   type MessageActionViewState,
@@ -39,6 +40,7 @@ function defaultUserFallback(message: ConversationViewMessage): React.ReactNode
     <div className="bubble" data-role="user">
       {message.quote && <div className="msg-quote">{message.quote.text}</div>}
       {message.text}
+      <UIMessageSupplementalParts message={message} />
     </div>
   )
 }
diff --git a/app/thread-chat/chat/message/editable-user-message.tsx b/app/thread-chat/chat/message/editable-user-message.tsx
index 04f52741..df337afa 100644
--- a/app/thread-chat/chat/message/editable-user-message.tsx
+++ b/app/thread-chat/chat/message/editable-user-message.tsx
@@ -9,6 +9,7 @@ import {
 } from "../actions/message-action-types"
 import { MessageToolbar } from "../actions/message-toolbar"
 import { useCopyMarkdown } from "../actions/use-copy-markdown"
+import { UIMessageSupplementalParts } from "./ui-message-parts"
 
 export function EditableUserMessage({
   threadId,
@@ -89,7 +90,10 @@ export function EditableUserMessage({
             </div>
           </>
         ) : (
-          message.text
+          <>
+            {message.text}
+            <UIMessageSupplementalParts message={message} />
+          </>
         )}
       </div>
       {!editing && (
diff --git a/app/thread-chat/chat/message/ui-message-parts.tsx b/app/thread-chat/chat/message/ui-message-parts.tsx
index 9f623d7d..65bd2d42 100644
--- a/app/thread-chat/chat/message/ui-message-parts.tsx
+++ b/app/thread-chat/chat/message/ui-message-parts.tsx
@@ -1,7 +1,179 @@
 "use client"
 
+import Image from "next/image"
+import { useEffect, useState } from "react"
+import { Download, FileText, RotateCcw } from "lucide-react"
+import {
+  Attachment,
+  AttachmentContent,
+  AttachmentDescription,
+  AttachmentMedia,
+  AttachmentTitle,
+} from "@/components/ui/attachment"
+import { Button } from "@/components/ui/button"
+import { Skeleton } from "@/components/ui/skeleton"
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogTitle,
+  DialogTrigger,
+} from "@/components/ui/dialog"
 import type { ConversationViewMessage } from "../../core/types"
 
+function attachmentTypeLabel(filename: string | undefined, mediaType: string) {
+  const extension = filename?.match(/\.([^.]+)$/)?.[1]
+  if (extension) return `${extension.toUpperCase()} 文件`
+  return mediaType === "text/plain" ? "文本文件" : "附件"
+}
+
+type MessageFilePart = Extract<
+  NonNullable<ConversationViewMessage["uiParts"]>[number],
+  { type: "file" }
+>
+
+type TextPreviewState =
+  | { status: "idle" | "loading" }
+  | { status: "ready"; content: string }
+  | { status: "error"; message: string }
+
+function TextAttachmentPreview({ part }: { part: MessageFilePart }) {
+  const [open, setOpen] = useState(false)
+  const [requestVersion, setRequestVersion] = useState(0)
+  const [preview, setPreview] = useState<TextPreviewState>({ status: "idle" })
+
+  useEffect(() => {
+    if (!open) return
+    const controller = new AbortController()
+    void fetch(`${part.url}/content`, {
+      cache: "no-store",
+      signal: controller.signal,
+    })
+      .then(async (response) => {
+        if (response.ok) return response.text()
+        const body = (await response.json().catch(() => null)) as {
+          error?: string
+        } | null
+        throw new Error(body?.error ?? "文件打开失败，请重试")
+      })
+      .then((content) => setPreview({ status: "ready", content }))
+      .catch((error) => {
+        if (error instanceof DOMException && error.name === "AbortError") return
+        setPreview({
+          status: "error",
+          message: error instanceof Error ? error.message : "文件打开失败，请重试",
+        })
+      })
+    return () => controller.abort()
+  }, [open, part.url, requestVersion])
+
+  const filename = part.filename ?? "附件"
+
+  return (
+    <Dialog
+      open={open}
+      onOpenChange={(nextOpen) => {
+        if (nextOpen) setPreview({ status: "loading" })
+        setOpen(nextOpen)
+      }}
+    >
+      <Attachment size="sm" className="w-[min(18rem,72vw)] flex-nowrap">
+        <AttachmentMedia aria-hidden="true">
+          <FileText />
+        </AttachmentMedia>
+        <AttachmentContent>
+          <AttachmentTitle title={filename}>{filename}</AttachmentTitle>
+          <AttachmentDescription>
+            {attachmentTypeLabel(part.filename, part.mediaType)}
+          </AttachmentDescription>
+        </AttachmentContent>
+        <DialogTrigger
+          render={
+            <button
+              type="button"
+              aria-label={`预览 ${filename}`}
+              className="absolute inset-0 z-10 cursor-pointer rounded-2xl outline-none focus-visible:ring-2 focus-visible:ring-ring"
+            />
+          }
+        />
+      </Attachment>
+      <DialogContent className="grid h-[min(80dvh,48rem)] max-h-[calc(100dvh-2rem)] grid-rows-[auto_minmax(0,1fr)_auto] gap-3 overflow-hidden p-4 sm:max-w-4xl">
+        <div className="min-w-0 pe-10">
+          <DialogTitle className="truncate">{filename}</DialogTitle>
+          <DialogDescription className="mt-1 text-xs">
+            {attachmentTypeLabel(part.filename, part.mediaType)}
+          </DialogDescription>
+        </div>
+        <div className="min-h-0 overflow-auto rounded-xl border bg-muted/30">
+          {(preview.status === "idle" || preview.status === "loading") && (
+            <div className="space-y-3 p-4" role="status">
+              <span className="sr-only">文件加载中</span>
+              <div className="space-y-3" aria-hidden="true">
+                <Skeleton className="h-3 w-2/5" />
+                <Skeleton className="h-3 w-full" />
+                <Skeleton className="h-3 w-11/12" />
+                <Skeleton className="h-3 w-4/5" />
+                <Skeleton className="h-3 w-full" />
+                <Skeleton className="h-3 w-3/4" />
+                <Skeleton className="h-3 w-5/6" />
+              </div>
+            </div>
+          )}
+          {preview.status === "error" && (
+            <div
+              className="flex min-h-full flex-col items-center justify-center gap-3 p-4 text-center"
+              role="alert"
+            >
+              <p>{preview.message}</p>
+              <Button
+                type="button"
+                variant="outline"
+                size="sm"
+                onClick={() => {
+                  setPreview({ status: "loading" })
+                  setRequestVersion((version) => version + 1)
+                }}
+              >
+                <RotateCcw aria-hidden="true" />
+                重试
+              </Button>
+            </div>
+          )}
+          {preview.status === "ready" &&
+            (preview.content ? (
+              <pre
+                className="m-0 min-h-full whitespace-pre-wrap break-words p-4 font-mono text-xs leading-5 text-foreground"
+                tabIndex={0}
+              >
+                {preview.content}
+              </pre>
+            ) : (
+              <div
+                className="flex min-h-full items-center justify-center p-4 text-muted-foreground"
+                role="status"
+              >
+                这个文件没有内容
+              </div>
+            ))}
+        </div>
+        <div className="flex justify-end">
+          <Button
+            variant="outline"
+            size="sm"
+            nativeButton={false}
+            render={
+              <a href={`${part.url}?download=1`} download={part.filename} />
+            }
+          >
+            <Download aria-hidden="true" />
+            下载文件
+          </Button>
+        </div>
+      </DialogContent>
+    </Dialog>
+  )
+}
+
 /**
  * text/data-artifact/data-research 仍由现有正文、Artifact 卡和研究面板渲染；
  * 这里仅补齐此前没有平行字段的 reasoning/source/file/tool parts。
@@ -39,11 +211,55 @@ export function UIMessageSupplementalParts({
           </div>
         </details>
       )}
-      {files.map((part, index) => (
-        <a key={`${part.url}-${index}`} href={part.url} download={part.filename}>
-          {part.filename ?? "附件"}
-        </a>
-      ))}
+      {files.length > 0 && (
+        <div
+          data-ui-message-files="true"
+          className="mt-2 ms-auto flex w-fit max-w-full flex-wrap justify-end gap-2"
+        >
+          {files.map((part, index) =>
+            part.mediaType.startsWith("image/") ? (
+              <Dialog key={`${part.url}-${index}`}>
+                <DialogTrigger
+                  type="button"
+                  aria-label={`预览 ${part.filename ?? "用户上传的图片"}`}
+                  className="block w-fit max-w-[min(18rem,72vw)] cursor-zoom-in rounded-md border-0 bg-transparent p-0 outline-none focus-visible:ring-2 focus-visible:ring-ring"
+                >
+                  <Image
+                    src={part.url}
+                    alt={part.filename ?? "用户上传的图片"}
+                    width={640}
+                    height={480}
+                    sizes="(max-width: 480px) 72vw, 288px"
+                    unoptimized
+                    className="h-auto max-h-48 w-auto max-w-full rounded-md object-contain"
+                  />
+                </DialogTrigger>
+                <DialogContent className="max-h-[calc(100dvh-2rem)] gap-0 overflow-hidden p-2 sm:max-w-5xl">
+                  <DialogTitle className="sr-only">
+                    {part.filename ?? "用户上传的图片"}
+                  </DialogTitle>
+                  <div className="flex max-h-[calc(100dvh-3rem)] min-h-32 items-center justify-center overflow-hidden">
+                    <Image
+                      src={part.url}
+                      alt={part.filename ?? "用户上传的图片"}
+                      width={2048}
+                      height={2048}
+                      sizes="calc(100vw - 3rem)"
+                      unoptimized
+                      className="h-auto max-h-[calc(100dvh-3rem)] w-auto max-w-full object-contain"
+                    />
+                  </div>
+                </DialogContent>
+              </Dialog>
+            ) : (
+              <TextAttachmentPreview
+                key={`${part.url}-${index}`}
+                part={part}
+              />
+            )
+          )}
+        </div>
+      )}
       {sources.map((part, index) => (
         <a
           key={`${part.url}-${index}`}
diff --git a/app/thread-chat/core/projections.ts b/app/thread-chat/core/projections.ts
index 07dafc53..0a08e38e 100644
--- a/app/thread-chat/core/projections.ts
+++ b/app/thread-chat/core/projections.ts
@@ -12,6 +12,7 @@ import type {
 } from "@/lib/thread-chat/contracts/dto"
 import type { NormalizedThreadChatState } from "./types"
 import type { MarkdownGenerationProgress } from "@/lib/thread-chat/domain/types"
+import { textFromMessageParts } from "@/lib/thread-chat/contracts/ui-message"
 import type { WebResearchActivity } from "@/lib/chat/web-research-activity"
 import type { ResearchPlan, ResearchRoute } from "@/lib/chat/research-router"
 import { THREAD_TREE_SCHEMA_VERSION } from "@/constants/thread-chat"
@@ -26,13 +27,7 @@ function dataPart<T>(
 }
 
 function messageText(message: MessageDTO): string {
-  return message.parts
-    .filter(
-      (part): part is Extract<typeof part, { type: "text" }> =>
-        part.type === "text"
-    )
-    .map((part) => part.text)
-    .join("")
+  return textFromMessageParts(message.parts)
 }
 
 function projectMessageState(
diff --git a/app/thread-chat/gate-3-harness/mock-v1-runtime.ts b/app/thread-chat/gate-3-harness/mock-v1-runtime.ts
index 8ecc2c3d..c3f98172 100644
--- a/app/thread-chat/gate-3-harness/mock-v1-runtime.ts
+++ b/app/thread-chat/gate-3-harness/mock-v1-runtime.ts
@@ -7,6 +7,7 @@ import type {
   ThreadDTO,
 } from "@/lib/thread-chat/contracts/dto"
 import { PROJECT_TITLE_FALLBACK } from "@/constants/project-workspace"
+import { textFromMessageParts } from "@/lib/thread-chat/contracts/ui-message"
 import type { ThreadChatClient } from "../net/client"
 
 export type Gate3HarnessScenario =
@@ -33,13 +34,7 @@ function now(): string {
 }
 
 function textOf(message: MessageDTO): string {
-  return message.parts
-    .filter(
-      (part): part is Extract<typeof part, { type: "text" }> =>
-        part.type === "text"
-    )
-    .map((part) => part.text)
-    .join("")
+  return textFromMessageParts(message.parts)
 }
 
 function commandResponse<T>(data: T) {
diff --git a/app/thread-chat/gate-3-harness/normalized-harness.tsx b/app/thread-chat/gate-3-harness/normalized-harness.tsx
index 31429b2e..53a13a1b 100644
--- a/app/thread-chat/gate-3-harness/normalized-harness.tsx
+++ b/app/thread-chat/gate-3-harness/normalized-harness.tsx
@@ -24,6 +24,7 @@ import type {
   ThreadMessageActionCommands,
 } from "../chat/actions/message-action-commands"
 import type { MessageActionViewState } from "../chat/actions/message-action-types"
+import { textFromMessageParts } from "@/lib/thread-chat/contracts/ui-message"
 import type { Message, MessageFeedback } from "../core/types"
 import { BranchableChat } from "../branching/branchable-chat"
 import {
@@ -258,10 +259,7 @@ export function NormalizedGate3Harness({
           assistantMessageId: assistant?.id,
           modelId:
             state.threadsById[threadId]?.modelId ?? "doubao-seed-2.1-turbo",
-          text: source.parts
-            .filter((part) => part.type === "text")
-            .map((part) => part.text)
-            .join(""),
+          text: textFromMessageParts(source.parts),
         })
         return actionResult({
           userMessageId: result.command.userMessageId,
diff --git a/app/thread-chat/styles/composer.css b/app/thread-chat/styles/composer.css
index 9e8238a9..0f5461e3 100644
--- a/app/thread-chat/styles/composer.css
+++ b/app/thread-chat/styles/composer.css
@@ -1,6 +1,8 @@
 /* ── @/thread-chat/styles ── 输入框 composer */
 
 /* ---------------- 输入框 ---------------- */
+/* 外壳不做视觉容器（无背景 / 无分隔线 / 不可命中）：整块区域鼠标穿透，
+   只有内部的 .box 输入框本体接收交互。 */
 .tc .composer {
   flex: none;
   border-top: 1px solid var(--tc-border-subtle);
@@ -101,3 +103,52 @@
   color: var(--tc-content-on-accent);
   background: var(--tc-accent);
 }
+
+/* ---------------- 附件能力（column 变体） ---------------- */
+.tc .composer .composer-tools {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  align-self: flex-start;
+}
+.tc .composer .attach-btn {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  width: 22px;
+  height: 22px;
+  padding: 0;
+  border: none;
+  border-radius: 6px;
+  cursor: pointer;
+  background: transparent;
+  color: var(--tc-content-secondary);
+}
+.tc .composer .attach-btn:hover {
+  background: var(--tc-accent-glow);
+}
+.tc .composer .box.attach-dragging {
+  border-color: var(--tc-accent);
+  background: color-mix(
+    in srgb,
+    var(--tc-accent) 4%,
+    var(--tc-surface-plain)
+  );
+}
+/* 附件卡片沿用卡片视觉但收敛到手稿尺寸；托盘单行横向滚动。 */
+.tc .composer .composer-attachment-tray {
+  display: flex;
+  gap: 6px;
+  overflow-x: auto;
+  padding: 2px 0 6px;
+  scrollbar-width: thin;
+}
+.tc .composer .composer-attachment-item {
+  border-color: var(--tc-border-strong);
+  border-radius: 8px;
+  background: var(--tc-surface-plain);
+  color: var(--tc-content-primary);
+}
+.tc .composer .composer-attachment-item .text-muted-foreground {
+  color: var(--tc-content-muted);
+}
diff --git a/app/thread-chat/thread-chat-demo.tsx b/app/thread-chat/thread-chat-demo.tsx
index 74725ea0..e595558e 100644
--- a/app/thread-chat/thread-chat-demo.tsx
+++ b/app/thread-chat/thread-chat-demo.tsx
@@ -6,6 +6,8 @@ import React, { useCallback, useEffect, useMemo, useState } from "react"
 
 import { DEFAULT_THREAD_CHAT_MODEL_ID } from "@/constants/model"
 import { PROJECT_TITLE_FALLBACK } from "@/constants/project-workspace"
+import type { MessageDTO } from "@/lib/thread-chat/contracts/dto"
+import { textFromMessageParts } from "@/lib/thread-chat/contracts/ui-message"
 import {
   activePathArtifacts,
   threadTitle,
@@ -35,6 +37,7 @@ import type {
 } from "./chat/actions/message-action-commands"
 import type { MessageActionViewState } from "./chat/actions/message-action-types"
 import { kickoffQuestion } from "./net/prompt/prompt-pure"
+import type { CommandFileReference } from "./net/commands/conversation-commands"
 import { removeWorkspaceState } from "./net/persistence/workspace-state"
 import { ThreadColumns } from "./orchestration/columns/thread-columns"
 import type {
@@ -80,6 +83,20 @@ function compactTitle(text: string, maxLength: number): string {
   return text.length > maxLength ? `${text.slice(0, maxLength)}…` : text
 }
 
+function messageFileReferences(message: MessageDTO): CommandFileReference[] {
+  return message.parts.flatMap((part) =>
+    part.type === "file"
+      ? [
+          {
+            url: part.url,
+            mediaType: part.mediaType,
+            ...(part.filename ? { filename: part.filename } : {}),
+          },
+        ]
+      : []
+  )
+}
+
 function legacyFeedback(value: "up" | "down" | null): MessageFeedback | null {
   return value === "up" ? "positive" : value === "down" ? "negative" : null
 }
@@ -265,10 +282,8 @@ function NormalizedThreadChat({
             modelId:
               state.threadsById[threadId]?.modelId ??
               DEFAULT_THREAD_CHAT_MODEL_ID,
-            text: source.parts
-              .filter((part) => part.type === "text")
-              .map((part) => part.text)
-              .join(""),
+            text: textFromMessageParts(source.parts),
+            files: messageFileReferences(source),
           })
           return actionResult({
             userMessageId: result.command.userMessageId,
@@ -298,6 +313,7 @@ function NormalizedThreadChat({
               state.threadsById[threadId]?.modelId ??
               DEFAULT_THREAD_CHAT_MODEL_ID,
             text,
+            files: source ? messageFileReferences(source) : [],
           })
           return actionResult({
             userMessageId: result.command.userMessageId,
@@ -328,7 +344,7 @@ function NormalizedThreadChat({
   )
 
   const send = useCallback(
-    (viewThreadId: string, text: string) => {
+    (viewThreadId: string, text: string, files: CommandFileReference[] = []) => {
       const current = runtime.store.getState()
       const normalizedThreadId = fromConversationViewThreadId(
         current,
@@ -340,11 +356,13 @@ function NormalizedThreadChat({
             modelId:
               current.threadsById[normalizedThreadId]?.modelId ?? draftModelId,
             text,
+            files,
           })
         : runtime.commands.startProject({
             projectId: treeId,
             modelId: draftModelId,
             text,
+            files,
           })
       void operation.catch((error) =>
         showToast(error instanceof Error ? error.message : "发送失败，请重试")
@@ -631,7 +649,7 @@ function NormalizedThreadChat({
                 }}
                 onRetry={(message) => retry(viewThreadId, message)}
                 onStop={() => stop(viewThreadId)}
-                onSend={(text) => send(viewThreadId, text)}
+                onSend={(text, files) => send(viewThreadId, text, files)}
                 messageActionState={messageActionState}
                 messageCommands={messageCommands}
               />
diff --git a/constants/attachment.ts b/constants/attachment.ts
index 180b81aa..738eae68 100644
--- a/constants/attachment.ts
+++ b/constants/attachment.ts
@@ -12,21 +12,124 @@ export type AttachmentPolicy = {
   ext: string
 }
 
+export const IMAGE_MODEL_VALIDATION_MESSAGE =
+  "当前模型不支持图片，请切换视觉模型或移除图片。"
+
 const MB = 1024 * 1024
 
+/** 图片附件 MVP 限制与压缩参数的单一来源。 */
+export const IMAGE_ATTACHMENT_MIME_TYPES = [
+  "image/png",
+  "image/jpeg",
+  "image/webp",
+] as const
+
+export type ImageAttachmentMimeType =
+  (typeof IMAGE_ATTACHMENT_MIME_TYPES)[number]
+
+export const IMAGE_ATTACHMENT_LIMITS = {
+  maxFilesPerMessage: 5,
+  maxBytesPerFile: 10 * MB,
+  maxLongestEdge: 2048,
+  lossyOutputMediaType: "image/webp",
+  lossyQuality: 0.8,
+} as const
+
+/** 短粘贴文本直接进入消息，避免语音转写产生无意义的附件上传。 */
+export const INLINE_PASTED_TEXT_CHAR_LIMIT = 4_000
+
+/** 作为 UTF-8 纯文本处理的常见文档与源码扩展名。 */
+export const TEXT_ATTACHMENT_FILE_EXTENSIONS = [
+  ".txt",
+  ".md",
+  ".markdown",
+  ".mdx",
+  ".js",
+  ".jsx",
+  ".mjs",
+  ".cjs",
+  ".ts",
+  ".tsx",
+  ".mts",
+  ".cts",
+  ".json",
+  ".jsonc",
+  ".html",
+  ".htm",
+  ".css",
+  ".scss",
+  ".sass",
+  ".less",
+  ".xml",
+  ".svg",
+  ".yaml",
+  ".yml",
+  ".toml",
+  ".ini",
+  ".conf",
+  ".config",
+  ".env",
+  ".py",
+  ".pyi",
+  ".rb",
+  ".php",
+  ".java",
+  ".kt",
+  ".kts",
+  ".go",
+  ".rs",
+  ".swift",
+  ".c",
+  ".h",
+  ".cc",
+  ".cpp",
+  ".cxx",
+  ".hpp",
+  ".cs",
+  ".sh",
+  ".bash",
+  ".zsh",
+  ".fish",
+  ".ps1",
+  ".bat",
+  ".cmd",
+  ".sql",
+  ".graphql",
+  ".gql",
+  ".proto",
+  ".vue",
+  ".svelte",
+] as const
+
 export const ATTACHMENT_POLICIES: Record<string, AttachmentPolicy> = {
+  "text/plain": { kind: "document", maxBytes: 20 * MB, ext: "txt" },
   "application/pdf": { kind: "document", maxBytes: 20 * MB, ext: "pdf" },
-  "image/png": { kind: "image", maxBytes: 10 * MB, ext: "png" },
-  "image/jpeg": { kind: "image", maxBytes: 10 * MB, ext: "jpg" },
-  "image/webp": { kind: "image", maxBytes: 10 * MB, ext: "webp" },
+  "image/png": {
+    kind: "image",
+    maxBytes: IMAGE_ATTACHMENT_LIMITS.maxBytesPerFile,
+    ext: "png",
+  },
+  "image/jpeg": {
+    kind: "image",
+    maxBytes: IMAGE_ATTACHMENT_LIMITS.maxBytesPerFile,
+    ext: "jpg",
+  },
+  "image/webp": {
+    kind: "image",
+    maxBytes: IMAGE_ATTACHMENT_LIMITS.maxBytesPerFile,
+    ext: "webp",
+  },
   "image/gif": { kind: "image", maxBytes: 10 * MB, ext: "gif" },
   "application/zip": { kind: "archive", maxBytes: 50 * MB, ext: "zip" },
   "video/mp4": { kind: "video", maxBytes: 100 * MB, ext: "mp4" },
   "video/webm": { kind: "video", maxBytes: 100 * MB, ext: "webm" },
 }
 
-/** Composer 文件选择器的 accept 属性（由策略表推导） */
-export const ATTACHMENT_ACCEPT = Object.keys(ATTACHMENT_POLICIES).join(",")
+/** 文件选择器的 accept 属性（上传策略 + 规范为纯文本的源码扩展名）。 */
+export const ATTACHMENT_ACCEPT = [
+  ...Object.keys(ATTACHMENT_POLICIES),
+  ...TEXT_ATTACHMENT_FILE_EXTENSIONS,
+].join(",")
 
 /** 附件在应用内的稳定访问路径前缀（消息 parts 里存的 URL；presigned URL 会过期，不能落库） */
 export const ATTACHMENT_URL_PREFIX = "/api/attachments/"
diff --git a/constants/model.ts b/constants/model.ts
index ef1d6701..535e5fd3 100644
--- a/constants/model.ts
+++ b/constants/model.ts
@@ -110,6 +110,8 @@ export type ChatModel = {
   umapisCredentialGroup?: UMAPISCredentialGroup
   /** 尚未定义价格与扣费策略的模型，只保留可用 token usage。 */
   unbilledPreview?: true
+  /** 是否允许把图片作为原始多模态输入发送给供应商。未知能力必须为 false。 */
+  supportsImageInput: boolean
   /** 模型可见的产品入口。 */
   surfaces: readonly ChatModelSurface[]
   /** 仅用于展示分组，不参与鉴权和路由。 */
@@ -137,6 +139,7 @@ function createUmapisClaudeModel<const TModelId extends UMAPISClaudeModelId>(
     reasoningTransport: "native",
     umapisCredentialGroup: "claude",
     unbilledPreview: true,
+    supportsImageInput: true,
     surfaces: ["thread"],
     creator: "anthropic",
   } as const satisfies ChatModel
@@ -155,6 +158,7 @@ function createPrivateRelayModel<
     upstreamModel,
     reasoningTransport: "native",
     unbilledPreview: true,
+    supportsImageInput: false,
     surfaces: ["thread"],
     creator: "openai",
   } as const satisfies ChatModel
@@ -168,6 +172,7 @@ const CHAT_MODEL_REGISTRY = [
     provider: "minimax",
     upstreamModel: "MiniMax-M2",
     reasoningTransport: "think-tags",
+    supportsImageInput: false,
     surfaces: ["linear"],
   },
   {
@@ -177,6 +182,7 @@ const CHAT_MODEL_REGISTRY = [
     provider: "deepseek",
     upstreamModel: "deepseek-chat",
     gatewayModel: "deepseek/deepseek-chat",
+    supportsImageInput: false,
     surfaces: ["linear"],
   },
   {
@@ -186,6 +192,7 @@ const CHAT_MODEL_REGISTRY = [
     provider: "openai",
     upstreamModel: "gpt-4o-mini",
     gatewayModel: "openai/gpt-4o-mini",
+    supportsImageInput: false,
     surfaces: ["linear"],
   },
   {
@@ -194,6 +201,7 @@ const CHAT_MODEL_REGISTRY = [
     description: "火山方舟 Coding Plan",
     provider: "ark",
     upstreamModel: "doubao-seed-2.1-turbo",
+    supportsImageInput: false,
     surfaces: ["linear", "thread"],
   },
   {
@@ -202,6 +210,7 @@ const CHAT_MODEL_REGISTRY = [
     description: "火山方舟 Coding Plan",
     provider: "ark",
     upstreamModel: "doubao-seed-2.0-lite",
+    supportsImageInput: false,
     surfaces: ["linear", "thread"],
   },
   {
@@ -210,6 +219,7 @@ const CHAT_MODEL_REGISTRY = [
     description: "火山方舟 Coding Plan",
     provider: "ark",
     upstreamModel: "minimax-m2.7",
+    supportsImageInput: false,
     surfaces: ["linear"],
   },
   {
@@ -218,6 +228,7 @@ const CHAT_MODEL_REGISTRY = [
     description: "火山方舟 Coding Plan",
     provider: "ark",
     upstreamModel: "minimax-m3",
+    supportsImageInput: false,
     surfaces: ["linear", "thread"],
   },
   {
@@ -226,6 +237,7 @@ const CHAT_MODEL_REGISTRY = [
     description: "火山方舟 Coding Plan",
     provider: "ark",
     upstreamModel: "glm-5.3",
+    supportsImageInput: false,
     surfaces: ["linear", "thread"],
   },
   {
@@ -234,6 +246,7 @@ const CHAT_MODEL_REGISTRY = [
     description: "火山方舟 Coding Plan",
     provider: "ark",
     upstreamModel: "deepseek-v4-flash",
+    supportsImageInput: false,
     surfaces: ["linear", "thread"],
   },
   {
@@ -242,6 +255,7 @@ const CHAT_MODEL_REGISTRY = [
     description: "火山方舟 Coding Plan",
     provider: "ark",
     upstreamModel: "deepseek-v4-pro",
+    supportsImageInput: false,
     surfaces: ["linear", "thread"],
   },
   {
@@ -250,6 +264,7 @@ const CHAT_MODEL_REGISTRY = [
     description: "火山方舟 Coding Plan",
     provider: "ark",
     upstreamModel: "kimi-k2.6",
+    supportsImageInput: true,
     surfaces: ["linear", "thread"],
   },
   {
@@ -258,6 +273,7 @@ const CHAT_MODEL_REGISTRY = [
     description: "火山方舟 Coding Plan",
     provider: "ark",
     upstreamModel: "kimi-k2.7-code",
+    supportsImageInput: false,
     surfaces: ["linear", "thread"],
   },
   createUmapisClaudeModel("claude-opus-4-6", "Claude Opus 4.6"),
@@ -295,6 +311,7 @@ const CHAT_MODEL_REGISTRY = [
     reasoningTransport: "native",
     umapisCredentialGroup: "gpt",
     unbilledPreview: true,
+    supportsImageInput: true,
     surfaces: ["thread"],
     creator: "openai",
   },
@@ -307,6 +324,7 @@ const CHAT_MODEL_REGISTRY = [
     reasoningTransport: "native",
     umapisCredentialGroup: "gpt",
     unbilledPreview: true,
+    supportsImageInput: true,
     surfaces: ["thread"],
     creator: "openai",
   },
@@ -359,6 +377,7 @@ const CHAT_MODEL_REGISTRY = [
     provider: "openrouter",
     upstreamModel: "openai/gpt-5.6-luna",
     reasoningTransport: "native",
+    supportsImageInput: false,
     surfaces: ["thread"],
     creator: "openai",
   },
@@ -368,6 +387,7 @@ const CHAT_MODEL_REGISTRY = [
     provider: "openrouter",
     upstreamModel: "openai/gpt-5.6-luna-pro",
     reasoningTransport: "native",
+    supportsImageInput: false,
     surfaces: ["thread"],
     creator: "openai",
   },
@@ -377,6 +397,7 @@ const CHAT_MODEL_REGISTRY = [
     provider: "openrouter",
     upstreamModel: "openai/gpt-5.6-terra",
     reasoningTransport: "native",
+    supportsImageInput: false,
     surfaces: ["thread"],
     creator: "openai",
   },
@@ -386,6 +407,7 @@ const CHAT_MODEL_REGISTRY = [
     provider: "openrouter",
     upstreamModel: "openai/gpt-5.6-terra-pro",
     reasoningTransport: "native",
+    supportsImageInput: false,
     surfaces: ["thread"],
     creator: "openai",
   },
@@ -395,6 +417,7 @@ const CHAT_MODEL_REGISTRY = [
     provider: "openrouter",
     upstreamModel: "openai/gpt-5.6-sol",
     reasoningTransport: "native",
+    supportsImageInput: true,
     surfaces: ["thread"],
     creator: "openai",
   },
@@ -404,6 +427,7 @@ const CHAT_MODEL_REGISTRY = [
     provider: "openrouter",
     upstreamModel: "openai/gpt-5.6-sol-pro",
     reasoningTransport: "native",
+    supportsImageInput: false,
     surfaces: ["thread"],
     creator: "openai",
   },
@@ -413,6 +437,7 @@ const CHAT_MODEL_REGISTRY = [
     provider: "openrouter",
     upstreamModel: "openai/gpt-5.5",
     reasoningTransport: "native",
+    supportsImageInput: false,
     surfaces: ["thread"],
     creator: "openai",
   },
@@ -422,6 +447,7 @@ const CHAT_MODEL_REGISTRY = [
     provider: "openrouter",
     upstreamModel: "openai/gpt-5.5-pro",
     reasoningTransport: "native",
+    supportsImageInput: false,
     surfaces: ["thread"],
     creator: "openai",
   },
@@ -431,6 +457,7 @@ const CHAT_MODEL_REGISTRY = [
     provider: "openrouter",
     upstreamModel: "moonshotai/kimi-k3",
     reasoningTransport: "native",
+    supportsImageInput: false,
     surfaces: ["thread"],
     creator: "moonshotai",
   },
@@ -440,6 +467,7 @@ const CHAT_MODEL_REGISTRY = [
     provider: "openrouter",
     upstreamModel: "deepseek/deepseek-v4-flash-0731",
     reasoningTransport: "native",
+    supportsImageInput: false,
     surfaces: ["thread"],
     creator: "deepseek",
   },
@@ -449,6 +477,7 @@ const CHAT_MODEL_REGISTRY = [
     provider: "openrouter",
     upstreamModel: "qwen/qwen3.8-max",
     reasoningTransport: "native",
+    supportsImageInput: false,
     surfaces: ["thread"],
     creator: "qwen",
   },
@@ -458,6 +487,7 @@ const CHAT_MODEL_REGISTRY = [
     provider: "openrouter",
     upstreamModel: "x-ai/grok-4.5",
     reasoningTransport: "native",
+    supportsImageInput: false,
     surfaces: ["thread"],
     creator: "x-ai",
   },
@@ -467,6 +497,7 @@ const CHAT_MODEL_REGISTRY = [
     provider: "openrouter",
     upstreamModel: "x-ai/grok-4.6",
     reasoningTransport: "native",
+    supportsImageInput: false,
     surfaces: ["thread"],
     creator: "x-ai",
   },
@@ -478,6 +509,7 @@ const CHAT_MODEL_REGISTRY = [
     upstreamModel: "stealth/ox-alpha",
     reasoningTransport: "native",
     unbilledPreview: true,
+    supportsImageInput: false,
     surfaces: ["thread"],
     creator: "stealth",
   },
@@ -512,6 +544,11 @@ export function getChatModel(id: string | undefined): ChatModel | undefined {
   return CHAT_MODELS.find((m) => m.id === id)
 }
 
+/** 未注册模型及未确认端点一律不获得图片输入能力。 */
+export function supportsModelImageInput(modelId: string | undefined): boolean {
+  return getChatModel(modelId)?.supportsImageInput === true
+}
+
 /** 未定义价格和额度策略的模型仅作为不扣费预览提供。 */
 export function isUnbilledPreviewModel(model: ChatModel): boolean {
   return model.unbilledPreview === true
diff --git a/e2e/observability/eval-foundation.test.mjs b/e2e/observability/eval-foundation.test.mjs
index 8baf113d..0e82403d 100644
--- a/e2e/observability/eval-foundation.test.mjs
+++ b/e2e/observability/eval-foundation.test.mjs
@@ -80,7 +80,7 @@ test("mode manifests are explicit, non-empty, unique, and dataset-compatible", a
   const smoke = resolveDefaultEvaluationManifest(cases, "smoke")
   const release = resolveDefaultEvaluationManifest(cases, "release")
   assert.equal(smoke.manifest.profile, "default")
-  assert.equal(smoke.cases.length, 9)
+  assert.equal(smoke.cases.length, 10)
   assert.equal(release.cases.length, cases.length)
   assert.deepEqual(
     release.manifest.caseIds,
diff --git a/e2e/thread-chat/conversation-composer.test.mjs b/e2e/thread-chat/conversation-composer.test.mjs
index d1479629..3d45fbef 100644
--- a/e2e/thread-chat/conversation-composer.test.mjs
+++ b/e2e/thread-chat/conversation-composer.test.mjs
@@ -4,10 +4,13 @@ import {
   composerSubmission,
   shouldSubmitComposerKey,
 } from "../../app/thread-chat/chat/composer/conversation-composer-logic.ts"
+import { shouldInlinePastedText } from "../../app/thread-chat/chat/composer/thread-attachment-model.ts"
 
 assert.equal(composerSubmission("  hello  ", false), "hello")
 assert.equal(composerSubmission("   \n ", false), null)
 assert.equal(composerSubmission("hello", true), null)
+assert.equal(shouldInlinePastedText("x".repeat(4_000)), true)
+assert.equal(shouldInlinePastedText("x".repeat(4_001)), false)
 assert.equal(composerMaxHeight("column"), 120)
 assert.equal(composerMaxHeight("canvas"), 68)
 
diff --git a/e2e/thread-chat/image-attachment-slice.test.mjs b/e2e/thread-chat/image-attachment-slice.test.mjs
new file mode 100644
index 00000000..161f402d
--- /dev/null
+++ b/e2e/thread-chat/image-attachment-slice.test.mjs
@@ -0,0 +1,220 @@
+import assert from "node:assert/strict"
+import { convertToModelMessages } from "ai"
+import {
+  getChatModel,
+  supportsModelImageInput,
+  UMAPIS_MODEL_IDS,
+} from "../../constants/model.ts"
+import {
+  IMAGE_ATTACHMENT_LIMITS,
+  IMAGE_MODEL_VALIDATION_MESSAGE,
+} from "../../constants/attachment.ts"
+import { validateAttachmentFile } from "../../lib/attachments/upload.ts"
+import {
+  imageFilenameWithExtension,
+  imageResizeDimensions,
+  resizedImageOutput,
+} from "../../lib/attachments/image.ts"
+import { canAddThreadImages } from "../../app/thread-chat/chat/composer/thread-attachment-model.ts"
+import {
+  applyImageFileMaterializations,
+  resolveAttachmentContext,
+} from "../../lib/chat/resolve-attachments.ts"
+import {
+  assertModelSupportsNewAttachments,
+  hasImageFileReferences,
+} from "../../lib/thread-chat/application/command-utils.ts"
+
+const firstId = "00000000-0000-4000-8000-000000000001"
+const secondId = "00000000-0000-4000-8000-000000000002"
+assert.deepEqual(IMAGE_ATTACHMENT_LIMITS, {
+  maxFilesPerMessage: 5,
+  maxBytesPerFile: 10 * 1024 * 1024,
+  maxLongestEdge: 2048,
+  lossyOutputMediaType: "image/webp",
+  lossyQuality: 0.8,
+})
+assert.deepEqual(imageResizeDimensions(4000, 2000), {
+  width: 2048,
+  height: 1024,
+})
+assert.deepEqual(imageResizeDimensions(1000, 1600), {
+  width: 1000,
+  height: 1600,
+})
+assert.deepEqual(imageResizeDimensions(1200, 3000), {
+  width: 819,
+  height: 2048,
+})
+assert.deepEqual(resizedImageOutput("image/png"), {
+  mediaType: "image/png",
+  extension: "png",
+})
+assert.deepEqual(resizedImageOutput("image/jpeg"), {
+  mediaType: "image/webp",
+  extension: "webp",
+  quality: 0.8,
+})
+assert.equal(imageFilenameWithExtension("screen.capture.jpg", "webp"), "screen.capture.webp")
+assert.throws(
+  () =>
+    validateAttachmentFile({
+      type: "image/png",
+      size: IMAGE_ATTACHMENT_LIMITS.maxBytesPerFile + 1,
+    }),
+  /文件超过大小上限（10MB）/
+)
+
+const composerImages = Array.from({ length: 4 }, (_, index) => ({
+  id: String(index),
+  file: { type: "image/png" },
+  status: "ready",
+  progress: 1,
+}))
+assert.equal(canAddThreadImages(composerImages, 1), true)
+assert.equal(canAddThreadImages(composerImages, 2), false)
+
+const files = [
+  {
+    url: `/api/attachments/${firstId}`,
+    mediaType: "image/png",
+    filename: "first.png",
+  },
+  {
+    url: `/api/attachments/${secondId}`,
+    mediaType: "image/jpeg",
+    filename: "second.jpg",
+  },
+]
+
+assert.equal(supportsModelImageInput("kimi-k2.6"), true)
+for (const upstreamModel of UMAPIS_MODEL_IDS) {
+  const modelId = `umapis-${upstreamModel}`
+  assert.equal(supportsModelImageInput(modelId), true, modelId)
+  assert.equal(getChatModel(modelId)?.supportsImageInput, true, modelId)
+}
+assert.equal(supportsModelImageInput("openrouter-gpt-5.6-sol"), true)
+assert.equal(supportsModelImageInput("private-relay-gpt-5.6-sol"), false)
+assert.equal(supportsModelImageInput("deepseek-v4-flash"), false)
+assert.equal(supportsModelImageInput("deepseek-v4-pro"), false)
+assert.equal(
+  supportsModelImageInput("openrouter-deepseek-v4-flash-0731"),
+  false
+)
+assert.equal(getChatModel("openrouter-gpt-5.6-sol")?.supportsImageInput, true)
+assert.equal(hasImageFileReferences(files), true)
+assert.throws(
+  () => assertModelSupportsNewAttachments("deepseek-v4-flash", files),
+  (error) => error?.code === "VALIDATION_ERROR" && error.message === IMAGE_MODEL_VALIDATION_MESSAGE
+)
+assert.doesNotThrow(() =>
+  assertModelSupportsNewAttachments("openrouter-gpt-5.6-sol", files)
+)
+assert.throws(
+  () =>
+    assertModelSupportsNewAttachments(
+      "kimi-k2.6",
+      Array.from({ length: 6 }, (_, index) => ({
+        url: `/api/attachments/00000000-0000-4000-8000-${String(index).padStart(12, "0")}`,
+        mediaType: "image/png",
+        filename: `${index}.png`,
+      }))
+    ),
+  (error) =>
+    error?.code === "VALIDATION_ERROR" &&
+    error.message === "单次最多添加 5 张图片"
+)
+
+const rows = new Map([
+  [
+    firstId,
+    {
+      id: firstId,
+      userId: "user-1",
+      key: "attachments/first.png",
+      filename: "first.png",
+      mimeType: "image/png",
+      size: 3,
+      kind: "image",
+      status: "ready",
+      pageCount: null,
+      pages: null,
+      summary: null,
+      suggestedQuestions: null,
+      error: null,
+      createdAt: new Date(),
+      updatedAt: new Date(),
+    },
+  ],
+  [
+    secondId,
+    {
+      id: secondId,
+      userId: "user-1",
+      key: "attachments/second.jpg",
+      filename: "second.jpg",
+      mimeType: "image/jpeg",
+      size: 2,
+      kind: "image",
+      status: "ready",
+      pageCount: null,
+      pages: null,
+      summary: null,
+      suggestedQuestions: null,
+      error: null,
+      createdAt: new Date(),
+      updatedAt: new Date(),
+    },
+  ],
+])
+const bytesByKey = new Map([
+  ["attachments/first.png", Uint8Array.from([1, 2, 3])],
+  ["attachments/second.jpg", Uint8Array.from([4, 5])],
+])
+const messages = [
+  {
+    id: "message-1",
+    role: "user",
+    parts: [{ type: "text", text: "依次描述两张图片" }, ...files.map((file) => ({ type: "file", ...file }))],
+  },
+]
+const loadRows = async () => rows
+const readObjectBytes = async (key) => bytesByKey.get(key)
+
+const visual = await resolveAttachmentContext({
+  messages,
+  userId: "user-1",
+  supportsImageInput: true,
+  loadRows,
+  readObjectBytes,
+})
+const converted = await convertToModelMessages(visual.messages)
+const materialized = applyImageFileMaterializations(converted, visual.imageFiles)
+const userContent = materialized[0].content
+assert.ok(Array.isArray(userContent))
+const imageParts = userContent.filter((part) => part.type === "file")
+assert.deepEqual(
+  imageParts.map((part) => [part.filename, part.mediaType, [...part.data.data]]),
+  [
+    ["first.png", "image/png", [1, 2, 3]],
+    ["second.jpg", "image/jpeg", [4, 5]],
+  ]
+)
+assert.ok(
+  messages[0].parts.every(
+    (part) => part.type !== "file" || part.url.startsWith("/api/attachments/")
+  )
+)
+
+const nonVisual = await resolveAttachmentContext({
+  messages,
+  userId: "user-1",
+  supportsImageInput: false,
+  loadRows,
+  readObjectBytes,
+})
+assert.equal(nonVisual.imageFiles.length, 0)
+assert.match(nonVisual.messages[0].parts[1].text, /当前模型不支持查看图片/)
+assert.match(nonVisual.messages[0].parts[2].text, /当前模型不支持查看图片/)
+
+console.log("image attachment slice tests passed")
diff --git a/e2e/thread-chat/normalized-client-store.test.mjs b/e2e/thread-chat/normalized-client-store.test.mjs
index c1093801..f284ffd8 100644
--- a/e2e/thread-chat/normalized-client-store.test.mjs
+++ b/e2e/thread-chat/normalized-client-store.test.mjs
@@ -89,6 +89,7 @@ function bootstrap(overrides = {}) {
     project: project(),
     threads: [thread()],
     messages: [message()],
+    files: [],
     artifacts: [],
     activeGenerationIds: [],
     ...overrides,
@@ -655,6 +656,76 @@ async function testRetryABC() {
   commands.dispose()
 }
 
+async function testCommandFilesPassThrough() {
+  const store = createConversationStore({ bootstrap: bootstrap({ messages: [] }) })
+  const file = {
+    url: `/api/attachments/${crypto.randomUUID()}`,
+    mediaType: "text/plain",
+    filename: "pasted.txt",
+  }
+  let seen
+  const assistant = message({
+    id: crypto.randomUUID(),
+    sequence: 2,
+    status: "generating",
+    error: null,
+    finishedAt: null,
+    parts: [],
+  })
+  const commands = createConversationCommands({
+    store,
+    networkAttempts: 1,
+    createId: () => crypto.randomUUID(),
+    client: {
+      async sendMessage(_threadId, command) {
+        seen = command
+        return {
+          ok: true,
+          replayed: false,
+          data: {
+            project: project(),
+            thread: thread(),
+            userMessage: message({ role: "user", parts: [] }),
+            assistantMessage: assistant,
+            streamUrl: "/files",
+          },
+        }
+      },
+      async getMessage() {
+        return { ...assistant, status: "completed", finishedAt: stamp }
+      },
+      async generateThreadTitle() {
+        return {
+          project: project(),
+          thread: thread(),
+          title: "测试项目",
+          generated: false,
+        }
+      },
+    },
+    fetch: async () =>
+      sseResponse([
+        {
+          type: "terminal",
+          message: { ...assistant, status: "completed", finishedAt: stamp },
+        },
+      ]),
+  })
+  const result = await commands.sendMessage({
+    threadId: thread().id,
+    modelId: "test/model",
+    text: "读取附件",
+    files: [file],
+  })
+  assert.deepEqual(seen.files, [file])
+  assert.deepEqual(
+    store.getState().messagesById[result.command.userMessageId].parts,
+    [{ type: "text", text: "读取附件" }, { type: "file", ...file }]
+  )
+  await result.connection.finished
+  commands.dispose()
+}
+
 async function testCommandNetworkRetryReusesFrozenPayload() {
   const store = createConversationStore({
     bootstrap: bootstrap({ messages: [] }),
@@ -1098,6 +1169,7 @@ await testAcceptedGenerationStartsConnectingBeforeFirstSse()
 await testBootstrapBackgroundPollAndWorkspace()
 await testOptimisticRollbackIsolation()
 await testRetryABC()
+await testCommandFilesPassThrough()
 await testCommandNetworkRetryReusesFrozenPayload()
 await testCommandTitleGenerationUpdatesStore()
 await testPartsProjectionAndWorkspaceIsolation()
diff --git a/e2e/thread-chat/text-attachment-slice.test.mjs b/e2e/thread-chat/text-attachment-slice.test.mjs
new file mode 100644
index 00000000..1b5eecc6
--- /dev/null
+++ b/e2e/thread-chat/text-attachment-slice.test.mjs
@@ -0,0 +1,127 @@
+import assert from "node:assert/strict"
+import {
+  renderTextAttachment,
+} from "../../lib/chat/attachment-content-resolver.ts"
+import {
+  isTextAttachmentFile,
+  normalizeAttachmentFile,
+  validateAttachmentFile,
+} from "../../lib/attachments/upload.ts"
+import {
+  isThreadComposerFile,
+  isThreadComposerImageFile,
+  THREAD_COMPOSER_ACCEPT,
+} from "../../app/thread-chat/chat/composer/thread-attachment-model.ts"
+import {
+  startProjectCommandSchema,
+} from "../../lib/thread-chat/contracts/commands.ts"
+import {
+  THREAD_MESSAGE_ATTACHMENT_MIME_TYPES,
+} from "../../lib/thread-chat/application/command-utils.ts"
+
+const sourceText = "export function demo() {\n  return 42\n}\n"
+for (const [filename, mediaType] of [
+  ["README.MD", "text/markdown"],
+  ["guide.markdown", "text/markdown"],
+  ["index.js", "text/javascript"],
+  ["types.ts", "video/mp2t"],
+  ["page.html", "text/html"],
+  ["document.xml", "application/xml"],
+  ["icon.svg", "image/svg+xml"],
+]) {
+  const sourceFile = new File([sourceText], filename, { type: mediaType })
+  const normalizedFile = normalizeAttachmentFile(sourceFile)
+  assert.equal(isTextAttachmentFile(sourceFile), true)
+  assert.equal(isThreadComposerFile(sourceFile), true)
+  assert.equal(normalizedFile.name, filename)
+  assert.equal(normalizedFile.type, "text/plain")
+  assert.equal(normalizedFile.lastModified, sourceFile.lastModified)
+  assert.equal(await normalizedFile.text(), sourceText)
+  assert.doesNotThrow(() => validateAttachmentFile(sourceFile))
+}
+
+const svgFile = new File(["<svg></svg>"], "icon.svg", {
+  type: "image/svg+xml",
+})
+assert.equal(isThreadComposerImageFile(svgFile), false)
+assert.ok(THREAD_COMPOSER_ACCEPT.split(",").includes(".md"))
+assert.ok(THREAD_COMPOSER_ACCEPT.split(",").includes(".js"))
+assert.ok(THREAD_COMPOSER_ACCEPT.split(",").includes(".svg"))
+
+const binaryFile = new File([Uint8Array.from([0, 1, 2])], "tool.exe", {
+  type: "application/octet-stream",
+})
+assert.equal(isTextAttachmentFile(binaryFile), false)
+assert.equal(isThreadComposerFile(binaryFile), false)
+assert.throws(() => validateAttachmentFile(binaryFile), /不支持的文件类型/)
+
+const id = crypto.randomUUID()
+const row = {
+  id,
+  userId: "user",
+  key: "attachments/plain.txt",
+  filename: 'code & "notes".txt',
+  mimeType: "text/plain",
+  size: 32,
+  kind: "document",
+  status: "ready",
+  pageCount: null,
+  pages: null,
+  summary: null,
+  suggestedQuestions: null,
+  error: null,
+  createdAt: new Date(),
+  updatedAt: new Date(),
+}
+
+const original = "function demo() {\n  return 42\n}\n\n尾行"
+const full = await renderTextAttachment(
+  row,
+  1_000,
+  async () => new TextEncoder().encode(original)
+)
+assert.equal(full.mode, "full")
+assert.match(full.text, /name="code &amp; &quot;notes&quot;\.txt" mime="text\/plain"/)
+assert.ok(full.text.includes(original), "必须原样保留换行与代码缩进")
+
+const truncated = await renderTextAttachment(
+  row,
+  12,
+  async () => new TextEncoder().encode(original)
+)
+assert.equal(truncated.mode, "fallback")
+assert.ok(truncated.text.includes(original.slice(0, 12)))
+assert.match(truncated.text, /已截断：附件正文超出本轮上下文预算/)
+
+const invalidUtf8 = await renderTextAttachment(
+  row,
+  100,
+  async () => Uint8Array.from([0xc3, 0x28])
+)
+assert.match(invalidUtf8.text, /文本附件解析失败：内容不是有效的 UTF-8 文本/)
+
+assert.deepEqual(THREAD_MESSAGE_ATTACHMENT_MIME_TYPES, [
+  "text/plain",
+  "image/png",
+  "image/jpeg",
+  "image/webp",
+])
+const parsed = startProjectCommandSchema.parse({
+  commandId: crypto.randomUUID(),
+  projectId: crypto.randomUUID(),
+  rootThreadId: crypto.randomUUID(),
+  userMessageId: crypto.randomUUID(),
+  assistantMessageId: crypto.randomUUID(),
+  modelId: "test/model",
+  text: "请阅读附件",
+  files: [
+    {
+      url: `/api/attachments/${id}`,
+      mediaType: "text/plain",
+      filename: row.filename,
+    },
+  ],
+})
+assert.equal(parsed.files[0].mediaType, "text/plain")
+
+console.log("text attachment slice tests passed")
diff --git a/e2e/thread-chat/ui-message-parts-rendering.test.mjs b/e2e/thread-chat/ui-message-parts-rendering.test.mjs
index c96a8b1a..9976aacd 100644
--- a/e2e/thread-chat/ui-message-parts-rendering.test.mjs
+++ b/e2e/thread-chat/ui-message-parts-rendering.test.mjs
@@ -30,4 +30,74 @@ assert.match(
   "reasoning 展开内容必须保留换行"
 )
 
-console.log("PASS  UIMessage parts renderer preserves reasoning order")
+const supplementalPartsSource = fs.readFileSync(
+  "app/thread-chat/chat/message/ui-message-parts.tsx",
+  "utf8"
+)
+const imageBranchStart = supplementalPartsSource.indexOf(
+  'part.mediaType.startsWith("image/")'
+)
+const imageBranchEnd = supplementalPartsSource.indexOf(
+  ") : (",
+  imageBranchStart
+)
+assert.ok(imageBranchStart >= 0 && imageBranchEnd > imageBranchStart)
+const imageBranch = supplementalPartsSource.slice(
+  imageBranchStart,
+  imageBranchEnd
+)
+assert.match(imageBranch, /<Dialog/)
+assert.match(imageBranch, /<DialogTrigger/)
+assert.match(imageBranch, /max-w-\[min\(18rem,72vw\)\]/)
+assert.equal((imageBranch.match(/src=\{part\.url\}/g) ?? []).length, 2)
+assert.doesNotMatch(imageBranch, /target="_blank"/)
+assert.doesNotMatch(imageBranch, /href=\{part\.url\}/)
+assert.match(supplementalPartsSource, /data-ui-message-files="true"/)
+assert.match(supplementalPartsSource, /ms-auto flex w-fit max-w-full/)
+assert.match(supplementalPartsSource, /function TextAttachmentPreview/)
+assert.match(supplementalPartsSource, /<Attachment[\s>]/)
+assert.match(supplementalPartsSource, /<AttachmentTitle/)
+assert.match(supplementalPartsSource, /<AttachmentDescription/)
+assert.match(
+  supplementalPartsSource,
+  /<DialogDescription className="mt-1 text-xs">/
+)
+assert.match(supplementalPartsSource, /fetch\(`\$\{part\.url\}\/content`/)
+assert.match(supplementalPartsSource, /aria-label=\{`预览 /)
+assert.match(supplementalPartsSource, /import \{ Skeleton \}/)
+assert.ok((supplementalPartsSource.match(/<Skeleton /g) ?? []).length >= 5)
+assert.match(supplementalPartsSource, /className="sr-only">文件加载中/)
+assert.doesNotMatch(supplementalPartsSource, /正在打开文件/)
+assert.doesNotMatch(supplementalPartsSource, /LoaderCircle/)
+assert.match(supplementalPartsSource, />\s*重试\s*</)
+assert.match(supplementalPartsSource, />\s*下载文件\s*</)
+assert.doesNotMatch(supplementalPartsSource, /纯文本预览/)
+assert.doesNotMatch(supplementalPartsSource, /不会执行文件中的 HTML/)
+assert.match(supplementalPartsSource, /nativeButton=\{false\}/)
+assert.match(supplementalPartsSource, /\?download=1/)
+
+const contentRouteSource = fs.readFileSync(
+  "app/api/attachments/[id]/content/route.ts",
+  "utf8"
+)
+assert.match(contentRouteSource, /getCurrentUserId\(\)/)
+assert.match(contentRouteSource, /eq\(attachments\.userId, userId\)/)
+assert.match(contentRouteSource, /row\.status !== "ready"/)
+assert.match(contentRouteSource, /row\.mimeType !== "text\/plain"/)
+assert.match(contentRouteSource, /getObjectBytes\(row\.key\)/)
+assert.match(contentRouteSource, /text\/plain; charset=utf-8/)
+assert.match(contentRouteSource, /private, no-store/)
+assert.doesNotMatch(contentRouteSource, /error: "未配置 R2/)
+assert.doesNotMatch(contentRouteSource, /error: ".*UTF-8/)
+
+const downloadRouteSource = fs.readFileSync(
+  "app/api/attachments/[id]/route.ts",
+  "utf8"
+)
+const r2Source = fs.readFileSync("lib/storage/r2.ts", "utf8")
+assert.match(downloadRouteSource, /searchParams\.get\("download"\) === "1"/)
+assert.match(r2Source, /ResponseContentDisposition/)
+
+console.log(
+  "PASS  UIMessage parts renderer previews text attachments without exposing R2"
+)
diff --git a/evals/agent/baselines/fixture-ci-v1.json b/evals/agent/baselines/fixture-ci-v1.json
index ccbab043..d9a9afdb 100644
--- a/evals/agent/baselines/fixture-ci-v1.json
+++ b/evals/agent/baselines/fixture-ci-v1.json
@@ -17,6 +17,10 @@
       "multimodal-synthetic-chart",
       "multimodal-text-attachment",
       "multimodal-corrupt-file",
+      "project-contract-target-instructions",
+      "project-file-pdf-grounding",
+      "project-contract-update-boundary",
+      "project-files-cross-project-isolation",
       "reliability-stop-terminal",
       "reliability-completed-lifecycle",
       "reliability-generation-failure",
@@ -31,11 +35,11 @@
       "search-provider-fallback-429",
       "search-empty-timeout"
     ],
-    "fingerprint": "a99ed038bd225b58bf31b3940d7905a44a4ea5191a40a2390ae47ec169b21406"
+    "fingerprint": "7ba6963238f0a77c3af57840018b31d2d2329cdf00412818330ab110f2d050a5"
   },
   "kind": "fixture",
-  "createdAt": "2026-08-29T00:00:00.000Z",
-  "datasetRevision": "4f17d6d5f2a3197573d097773b14b3574c4b7fb79ee265e755452b88ac851d5a",
+  "createdAt": "2026-09-04T13:29:53.613Z",
+  "datasetRevision": "16384285a65ad16bc39fab0089334e0aa84f4d3e84a873e194d8c49d5a2a93fe",
   "candidateFingerprint": "9b84412630b72ddeecd0b8758d91907d0ae17cf81c31a98320a0aa3965dd13c6",
   "candidate": {
     "candidate": "fixture-baseline-v1",
@@ -54,7 +58,7 @@
   },
   "experimentUrl": null,
   "aggregate": {
-    "cases": 23,
+    "cases": 27,
     "hardFailures": 0,
     "p50LatencyMs": 0,
     "p95LatencyMs": 1,
@@ -67,7 +71,7 @@
     "providerAttempts": 6,
     "fallbackRate": 0.16666666666666666,
     "errorRate": 0,
-    "emptyOutputRate": 0.08695652173913043,
+    "emptyOutputRate": 0.07407407407407407,
     "estimatedCostUsd": null
   },
   "cases": [
@@ -76,7 +80,7 @@
       "suite": "core-answer",
       "hardFailures": [],
       "judgeScores": {},
-      "latencyMs": 1,
+      "latencyMs": 2,
       "usage": {},
       "providerAttempts": 0,
       "providerFailures": 0,
@@ -87,7 +91,7 @@
       "suite": "core-answer",
       "hardFailures": [],
       "judgeScores": {},
-      "latencyMs": 1,
+      "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
       "providerFailures": 0,
@@ -168,7 +172,7 @@
       "suite": "multimodal",
       "hardFailures": [],
       "judgeScores": {},
-      "latencyMs": 1,
+      "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
       "providerFailures": 0,
@@ -179,6 +183,50 @@
       "suite": "multimodal",
       "hardFailures": [],
       "judgeScores": {},
+      "latencyMs": 1,
+      "usage": {},
+      "providerAttempts": 0,
+      "providerFailures": 0,
+      "errorCategory": null
+    },
+    {
+      "caseId": "project-contract-target-instructions",
+      "suite": "memory-context",
+      "hardFailures": [],
+      "judgeScores": {},
+      "latencyMs": 0,
+      "usage": {},
+      "providerAttempts": 0,
+      "providerFailures": 0,
+      "errorCategory": null
+    },
+    {
+      "caseId": "project-file-pdf-grounding",
+      "suite": "multimodal",
+      "hardFailures": [],
+      "judgeScores": {},
+      "latencyMs": 0,
+      "usage": {},
+      "providerAttempts": 0,
+      "providerFailures": 0,
+      "errorCategory": null
+    },
+    {
+      "caseId": "project-contract-update-boundary",
+      "suite": "memory-context",
+      "hardFailures": [],
+      "judgeScores": {},
+      "latencyMs": 0,
+      "usage": {},
+      "providerAttempts": 0,
+      "providerFailures": 0,
+      "errorCategory": null
+    },
+    {
+      "caseId": "project-files-cross-project-isolation",
+      "suite": "memory-context",
+      "hardFailures": [],
+      "judgeScores": {},
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
diff --git a/evals/agent/baselines/fixture-scheduled-v1.json b/evals/agent/baselines/fixture-scheduled-v1.json
index fd781022..cb57ce05 100644
--- a/evals/agent/baselines/fixture-scheduled-v1.json
+++ b/evals/agent/baselines/fixture-scheduled-v1.json
@@ -22,6 +22,10 @@
       "multimodal-text-attachment",
       "multimodal-corrupt-file",
       "multimodal-unsupported-and-size-boundary",
+      "project-contract-target-instructions",
+      "project-file-pdf-grounding",
+      "project-contract-update-boundary",
+      "project-files-cross-project-isolation",
       "reliability-stop-terminal",
       "reliability-completed-lifecycle",
       "reliability-generation-failure",
@@ -40,11 +44,11 @@
       "search-provider-fallback-429",
       "search-empty-timeout"
     ],
-    "fingerprint": "05cb873bc2b4a4cfbc99f9ea30d309d0ff897a28099bfc0e413519b26669c999"
+    "fingerprint": "d11c50394561f55f03ce7432d8dcfe8ae686521f11cf84b19913e667d6d25cba"
   },
   "kind": "fixture",
-  "createdAt": "2026-08-29T00:00:00.000Z",
-  "datasetRevision": "4f17d6d5f2a3197573d097773b14b3574c4b7fb79ee265e755452b88ac851d5a",
+  "createdAt": "2026-09-04T13:29:53.395Z",
+  "datasetRevision": "16384285a65ad16bc39fab0089334e0aa84f4d3e84a873e194d8c49d5a2a93fe",
   "candidateFingerprint": "9b84412630b72ddeecd0b8758d91907d0ae17cf81c31a98320a0aa3965dd13c6",
   "candidate": {
     "candidate": "fixture-baseline-v1",
@@ -63,10 +67,10 @@
   },
   "experimentUrl": null,
   "aggregate": {
-    "cases": 32,
+    "cases": 36,
     "hardFailures": 0,
     "p50LatencyMs": 0,
-    "p95LatencyMs": 0,
+    "p95LatencyMs": 1,
     "totalUsage": {
       "inputTokens": 12,
       "outputTokens": 18,
@@ -76,7 +80,7 @@
     "providerAttempts": 8,
     "fallbackRate": 0.125,
     "errorRate": 0,
-    "emptyOutputRate": 0.0625,
+    "emptyOutputRate": 0.05555555555555555,
     "estimatedCostUsd": null
   },
   "cases": [
@@ -249,6 +253,50 @@
       "providerFailures": 0,
       "errorCategory": null
     },
+    {
+      "caseId": "project-contract-target-instructions",
+      "suite": "memory-context",
+      "hardFailures": [],
+      "judgeScores": {},
+      "latencyMs": 0,
+      "usage": {},
+      "providerAttempts": 0,
+      "providerFailures": 0,
+      "errorCategory": null
+    },
+    {
+      "caseId": "project-file-pdf-grounding",
+      "suite": "multimodal",
+      "hardFailures": [],
+      "judgeScores": {},
+      "latencyMs": 0,
+      "usage": {},
+      "providerAttempts": 0,
+      "providerFailures": 0,
+      "errorCategory": null
+    },
+    {
+      "caseId": "project-contract-update-boundary",
+      "suite": "memory-context",
+      "hardFailures": [],
+      "judgeScores": {},
+      "latencyMs": 0,
+      "usage": {},
+      "providerAttempts": 0,
+      "providerFailures": 0,
+      "errorCategory": null
+    },
+    {
+      "caseId": "project-files-cross-project-isolation",
+      "suite": "memory-context",
+      "hardFailures": [],
+      "judgeScores": {},
+      "latencyMs": 0,
+      "usage": {},
+      "providerAttempts": 0,
+      "providerFailures": 0,
+      "errorCategory": null
+    },
     {
       "caseId": "reliability-stop-terminal",
       "suite": "reliability",
@@ -386,7 +434,7 @@
       "suite": "search-routing",
       "hardFailures": [],
       "judgeScores": {},
-      "latencyMs": 0,
+      "latencyMs": 1,
       "usage": {},
       "providerAttempts": 1,
       "providerFailures": 0,
diff --git a/evals/agent/baselines/fixture-v1.json b/evals/agent/baselines/fixture-v1.json
index 2217a0a6..064d1407 100644
--- a/evals/agent/baselines/fixture-v1.json
+++ b/evals/agent/baselines/fixture-v1.json
@@ -22,6 +22,10 @@
       "multimodal-text-attachment",
       "multimodal-corrupt-file",
       "multimodal-unsupported-and-size-boundary",
+      "project-contract-target-instructions",
+      "project-file-pdf-grounding",
+      "project-contract-update-boundary",
+      "project-files-cross-project-isolation",
       "reliability-stop-terminal",
       "reliability-completed-lifecycle",
       "reliability-generation-failure",
@@ -40,39 +44,43 @@
       "search-provider-fallback-429",
       "search-empty-timeout"
     ],
-    "fingerprint": "7c4b4a2455187688621824e3688c9980a0c8693e783e0741365770611a939f10"
+    "fingerprint": "3531bc37b454db9abca9de888961b31af627b6ea83b644f6a79c7460613d6195"
   },
   "kind": "fixture",
-  "createdAt": "2026-08-28T00:00:00.000Z",
-  "datasetRevision": "4f17d6d5f2a3197573d097773b14b3574c4b7fb79ee265e755452b88ac851d5a",
+  "createdAt": "2026-09-04T13:30:18.881Z",
+  "datasetRevision": "16384285a65ad16bc39fab0089334e0aa84f4d3e84a873e194d8c49d5a2a93fe",
   "candidateFingerprint": "9b84412630b72ddeecd0b8758d91907d0ae17cf81c31a98320a0aa3965dd13c6",
   "candidate": {
     "candidate": "fixture-baseline-v1",
+    "commit": "f23dedb",
+    "contextPolicy": "fixture-context-v1",
+    "environment": "evaluation",
+    "evaluatorVersion": "deterministic-v1",
+    "memoryPolicyVersion": "thread-context-v1",
     "model": "umapis-claude-opus-4-6",
+    "multimodalParserVersion": "attachment-parser-v1",
     "promptVersion": "thread-chat-prompt-v1",
+    "release": "baseline-v1",
     "searchPolicyVersion": "anysearch-v1",
     "searchProvider": "anysearch",
-    "memoryPolicyVersion": "thread-context-v1",
-    "contextPolicy": "fixture-context-v1",
-    "toolsetVersion": "thread-chat-tools-v1",
-    "multimodalParserVersion": "attachment-parser-v1",
-    "release": "baseline-v1",
-    "commit": "f23dedb",
-    "environment": "evaluation",
-    "evaluatorVersion": "deterministic-v1"
+    "toolsetVersion": "thread-chat-tools-v1"
   },
   "experimentUrl": null,
   "aggregate": {
-    "cases": 32,
+    "cases": 36,
     "hardFailures": 0,
     "p50LatencyMs": 0,
-    "p95LatencyMs": 0,
-    "totalUsage": { "inputTokens": 12, "outputTokens": 18, "totalTokens": 30 },
+    "p95LatencyMs": 1,
+    "totalUsage": {
+      "inputTokens": 12,
+      "outputTokens": 18,
+      "totalTokens": 30
+    },
     "toolCalls": 10,
     "providerAttempts": 8,
     "fallbackRate": 0.125,
     "errorRate": 0,
-    "emptyOutputRate": 0.0625,
+    "emptyOutputRate": 0.05555555555555555,
     "estimatedCostUsd": null
   },
   "cases": [
@@ -81,9 +89,10 @@
       "suite": "core-answer",
       "hardFailures": [],
       "judgeScores": {},
-      "latencyMs": 0,
+      "latencyMs": 1,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -94,6 +103,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -104,6 +114,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -112,8 +123,13 @@
       "hardFailures": [],
       "judgeScores": {},
       "latencyMs": 0,
-      "usage": { "inputTokens": 12, "outputTokens": 18, "totalTokens": 30 },
+      "usage": {
+        "inputTokens": 12,
+        "outputTokens": 18,
+        "totalTokens": 30
+      },
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -124,6 +140,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -134,6 +151,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -144,6 +162,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -154,6 +173,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -164,6 +184,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -174,6 +195,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -184,6 +206,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -194,6 +217,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -204,6 +228,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -214,6 +239,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -224,6 +250,51 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
+      "errorCategory": null
+    },
+    {
+      "caseId": "project-contract-target-instructions",
+      "suite": "memory-context",
+      "hardFailures": [],
+      "judgeScores": {},
+      "latencyMs": 0,
+      "usage": {},
+      "providerAttempts": 0,
+      "providerFailures": 0,
+      "errorCategory": null
+    },
+    {
+      "caseId": "project-file-pdf-grounding",
+      "suite": "multimodal",
+      "hardFailures": [],
+      "judgeScores": {},
+      "latencyMs": 0,
+      "usage": {},
+      "providerAttempts": 0,
+      "providerFailures": 0,
+      "errorCategory": null
+    },
+    {
+      "caseId": "project-contract-update-boundary",
+      "suite": "memory-context",
+      "hardFailures": [],
+      "judgeScores": {},
+      "latencyMs": 0,
+      "usage": {},
+      "providerAttempts": 0,
+      "providerFailures": 0,
+      "errorCategory": null
+    },
+    {
+      "caseId": "project-files-cross-project-isolation",
+      "suite": "memory-context",
+      "hardFailures": [],
+      "judgeScores": {},
+      "latencyMs": 0,
+      "usage": {},
+      "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -234,6 +305,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -244,6 +316,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -251,9 +324,10 @@
       "suite": "reliability",
       "hardFailures": [],
       "judgeScores": {},
-      "latencyMs": 0,
+      "latencyMs": 1,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -264,6 +338,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -274,6 +349,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -284,6 +360,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 1,
+      "providerFailures": 1,
       "errorCategory": null
     },
     {
@@ -294,6 +371,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -304,6 +382,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -314,6 +393,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -324,6 +404,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -334,6 +415,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 0,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -344,6 +426,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 1,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -354,6 +437,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 1,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -364,6 +448,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 1,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -374,6 +459,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 1,
+      "providerFailures": 0,
       "errorCategory": null
     },
     {
@@ -384,6 +470,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 2,
+      "providerFailures": 1,
       "errorCategory": null
     },
     {
@@ -394,6 +481,7 @@
       "latencyMs": 0,
       "usage": {},
       "providerAttempts": 1,
+      "providerFailures": 1,
       "errorCategory": null
     }
   ]
diff --git a/lib/attachments/image.ts b/lib/attachments/image.ts
new file mode 100644
index 00000000..728b4233
--- /dev/null
+++ b/lib/attachments/image.ts
@@ -0,0 +1,83 @@
+"use client"
+
+import {
+  IMAGE_ATTACHMENT_LIMITS,
+  IMAGE_ATTACHMENT_MIME_TYPES,
+  type ImageAttachmentMimeType,
+} from "@/constants/attachment"
+
+export function isImageAttachmentMimeType(
+  mediaType: string
+): mediaType is ImageAttachmentMimeType {
+  return (IMAGE_ATTACHMENT_MIME_TYPES as readonly string[]).includes(mediaType)
+}
+
+export function imageResizeDimensions(
+  width: number,
+  height: number,
+  maxLongestEdge = IMAGE_ATTACHMENT_LIMITS.maxLongestEdge
+): { width: number; height: number } {
+  const longestEdge = Math.max(width, height)
+  if (longestEdge <= maxLongestEdge) return { width, height }
+  const scale = maxLongestEdge / longestEdge
+  return {
+    width: Math.max(1, Math.round(width * scale)),
+    height: Math.max(1, Math.round(height * scale)),
+  }
+}
+
+export function resizedImageOutput(mediaType: ImageAttachmentMimeType): {
+  mediaType: ImageAttachmentMimeType
+  extension: string
+  quality?: number
+} {
+  if (mediaType === "image/png") {
+    return { mediaType, extension: "png" }
+  }
+  return {
+    mediaType: IMAGE_ATTACHMENT_LIMITS.lossyOutputMediaType,
+    extension: "webp",
+    quality: IMAGE_ATTACHMENT_LIMITS.lossyQuality,
+  }
+}
+
+export function imageFilenameWithExtension(
+  filename: string,
+  extension: string
+): string {
+  const basename = filename.replace(/\.[^.]*$/, "") || "image"
+  return `${basename}.${extension}`
+}
+
+export async function preprocessImageAttachment(file: File): Promise<File> {
+  if (!isImageAttachmentMimeType(file.type)) return file
+  const bitmap = await createImageBitmap(file)
+  try {
+    const dimensions = imageResizeDimensions(bitmap.width, bitmap.height)
+    if (dimensions.width === bitmap.width && dimensions.height === bitmap.height) {
+      return file
+    }
+    const canvas = document.createElement("canvas")
+    canvas.width = dimensions.width
+    canvas.height = dimensions.height
+    const context = canvas.getContext("2d")
+    if (!context) throw new Error("浏览器无法处理图片")
+    context.drawImage(bitmap, 0, 0, dimensions.width, dimensions.height)
+    const output = resizedImageOutput(file.type)
+    const blob = await new Promise<Blob>((resolve, reject) => {
+      canvas.toBlob(
+        (value) =>
+          value ? resolve(value) : reject(new Error("图片压缩失败，请重试")),
+        output.mediaType,
+        output.quality
+      )
+    })
+    return new File(
+      [blob],
+      imageFilenameWithExtension(file.name, output.extension),
+      { type: output.mediaType, lastModified: file.lastModified }
+    )
+  } finally {
+    bitmap.close()
+  }
+}
diff --git a/lib/attachments/upload.ts b/lib/attachments/upload.ts
new file mode 100644
index 00000000..bd702542
--- /dev/null
+++ b/lib/attachments/upload.ts
@@ -0,0 +1,144 @@
+"use client"
+
+import {
+  ATTACHMENT_POLICIES,
+  ATTACHMENT_URL_PREFIX,
+  TEXT_ATTACHMENT_FILE_EXTENSIONS,
+  type AttachmentKind,
+} from "@/constants/attachment"
+
+export type AttachmentUploadStatus = "uploading" | "ready" | "error"
+
+export interface UploadedAttachmentReference {
+  url: string
+  mediaType: string
+  filename?: string
+}
+
+export interface AttachmentUploadResult {
+  serverId: string
+  reference: UploadedAttachmentReference
+}
+
+export interface AttachmentUploadOptions {
+  onProgress?: (progress: number) => void
+  fetch?: typeof globalThis.fetch
+}
+
+export interface AttachmentUploadValidation {
+  kind: AttachmentKind
+}
+
+export function isTextAttachmentFile(
+  file: Pick<File, "name" | "type">
+): boolean {
+  if (file.type === "text/plain") return true
+  const filename = file.name?.toLowerCase()
+  return Boolean(
+    filename &&
+      TEXT_ATTACHMENT_FILE_EXTENSIONS.some((extension) =>
+        filename.endsWith(extension)
+      )
+  )
+}
+
+export function normalizeAttachmentFile(file: File): File {
+  if (!isTextAttachmentFile(file) || file.type === "text/plain") return file
+  return new File([file], file.name, {
+    type: "text/plain",
+    lastModified: file.lastModified,
+  })
+}
+
+export function validateAttachmentFile(file: File): AttachmentUploadValidation {
+  const normalizedFile = normalizeAttachmentFile(file)
+  const policy = ATTACHMENT_POLICIES[normalizedFile.type]
+  if (!policy) throw new Error(`不支持的文件类型：${file.type || "未知"}`)
+  if (file.size > policy.maxBytes) {
+    throw new Error(
+      `文件超过大小上限（${Math.floor(policy.maxBytes / (1024 * 1024))}MB）`
+    )
+  }
+  return { kind: policy.kind }
+}
+
+function putWithProgress(
+  url: string,
+  file: File,
+  onProgress: (progress: number) => void
+) {
+  return new Promise<void>((resolve, reject) => {
+    const xhr = new XMLHttpRequest()
+    xhr.open("PUT", url)
+    xhr.setRequestHeader("Content-Type", file.type)
+    xhr.upload.onprogress = (event) => {
+      if (event.lengthComputable) onProgress(event.loaded / event.total)
+    }
+    xhr.onload = () =>
+      xhr.status >= 200 && xhr.status < 300
+        ? resolve()
+        : reject(new Error(`上传失败（HTTP ${xhr.status}）`))
+    xhr.onerror = () =>
+      reject(new Error("上传失败（网络错误，或 R2 桶未配置 CORS）"))
+    xhr.send(file)
+  })
+}
+
+async function readError(response: Response, fallback: string) {
+  const body = (await response.json().catch(() => null)) as {
+    error?: string
+  } | null
+  return body?.error ?? fallback
+}
+
+export async function uploadAttachment(
+  file: File,
+  options: AttachmentUploadOptions = {}
+): Promise<AttachmentUploadResult> {
+  const normalizedFile = normalizeAttachmentFile(file)
+  validateAttachmentFile(normalizedFile)
+  const request = options.fetch ?? globalThis.fetch
+  const onProgress = options.onProgress ?? (() => {})
+  const createResponse = await request("/api/attachments", {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: JSON.stringify({
+      filename: normalizedFile.name,
+      contentType: normalizedFile.type,
+      size: normalizedFile.size,
+    }),
+  })
+  if (!createResponse.ok)
+    throw new Error(await readError(createResponse, "创建附件失败"))
+  const { id, uploadUrl } = (await createResponse.json()) as {
+    id: string
+    uploadUrl: string
+  }
+
+  await putWithProgress(uploadUrl, normalizedFile, (progress) =>
+    onProgress(progress * 0.9)
+  )
+  onProgress(0.9)
+
+  const ingestResponse = await request(`/api/attachments/${id}/ingest`, {
+    method: "POST",
+  })
+  if (!ingestResponse.ok)
+    throw new Error(await readError(ingestResponse, "附件处理失败"))
+  onProgress(1)
+  return {
+    serverId: id,
+    reference: {
+      url: `${ATTACHMENT_URL_PREFIX}${id}`,
+      mediaType: normalizedFile.type,
+      ...(normalizedFile.name ? { filename: normalizedFile.name } : {}),
+    },
+  }
+}
+
+export async function deleteUploadedAttachment(serverId: string): Promise<void> {
+  const response = await fetch(`/api/attachments/${serverId}`, {
+    method: "DELETE",
+  })
+  if (!response.ok) throw new Error(await readError(response, "移除附件失败"))
+}
diff --git a/lib/chat/attachment-adapter.ts b/lib/chat/attachment-adapter.ts
index 198da645..a5407523 100644
--- a/lib/chat/attachment-adapter.ts
+++ b/lib/chat/attachment-adapter.ts
@@ -13,6 +13,12 @@ import {
   ATTACHMENT_URL_PREFIX,
   type AttachmentKind,
 } from "@/constants/attachment"
+import {
+  deleteUploadedAttachment,
+  normalizeAttachmentFile,
+  uploadAttachment,
+  validateAttachmentFile,
+} from "@/lib/attachments/upload"
 
 // 覆盖 react-ai-sdk 默认的 vercelAttachmentAdapter（base64 内联进消息 → 撑爆 Postgres jsonb）。
 // 策略：选中文件即上传 R2 + 服务端解析（与用户打字并行），点发送时零等待。
@@ -45,6 +51,10 @@ const KIND_TO_ATTACHMENT_TYPE: Record<AttachmentKind, Attachment["type"]> = {
   video: "file",
 }
 
+function attachmentKindOrNull(file: File): AttachmentKind | null {
+  return ATTACHMENT_POLICIES[file.type]?.kind ?? null
+}
+
 /** 单消费者异步通道：把 XHR 的 progress 回调转成 add() 里可 for-await 的进度流 */
 function createProgressChannel() {
   const queue: number[] = []
@@ -70,97 +80,36 @@ function createProgressChannel() {
   }
 }
 
-function putWithProgress(
-  url: string,
-  file: File,
-  onProgress: (progress: number) => void
-) {
-  return new Promise<void>((resolve, reject) => {
-    const xhr = new XMLHttpRequest()
-    xhr.open("PUT", url)
-    // Content-Type 参与了 presign 签名，必须与服务端签发时完全一致
-    xhr.setRequestHeader("Content-Type", file.type)
-    xhr.upload.onprogress = (e) => {
-      if (e.lengthComputable) onProgress(e.loaded / e.total)
-    }
-    xhr.onload = () =>
-      xhr.status >= 200 && xhr.status < 300
-        ? resolve()
-        : reject(new Error(`上传失败（HTTP ${xhr.status}）`))
-    xhr.onerror = () =>
-      reject(new Error("上传失败（网络错误，或 R2 桶未配置 CORS）"))
-    xhr.send(file)
-  })
-}
-
-async function readError(res: Response, fallback: string) {
-  const body = (await res.json().catch(() => null)) as { error?: string } | null
-  return body?.error ?? fallback
-}
-
-async function uploadAndIngest(
-  file: File,
-  onProgress: (progress: number) => void
-): Promise<UploadResult> {
-  const createRes = await fetch("/api/attachments", {
-    method: "POST",
-    headers: { "Content-Type": "application/json" },
-    body: JSON.stringify({
-      filename: file.name,
-      contentType: file.type,
-      size: file.size,
-    }),
-  })
-  if (!createRes.ok) throw new Error(await readError(createRes, "创建附件失败"))
-  const { id, uploadUrl } = (await createRes.json()) as {
-    id: string
-    uploadUrl: string
-  }
-
-  // 直传阶段占进度条 0~90%，剩余留给服务端解析
-  await putWithProgress(uploadUrl, file, (p) => onProgress(p * 0.9))
-  onProgress(0.9)
-
-  const ingestRes = await fetch(`/api/attachments/${id}/ingest`, {
-    method: "POST",
-  })
-  if (!ingestRes.ok) throw new Error(await readError(ingestRes, "附件处理失败"))
-  onProgress(1)
-  return { serverId: id }
-}
 
 export const r2AttachmentAdapter: AttachmentAdapter = {
   accept: ATTACHMENT_ACCEPT,
 
   async *add({ file }): AsyncGenerator<PendingAttachment, void> {
-    const policy = ATTACHMENT_POLICIES[file.type]
+    const normalizedFile = normalizeAttachmentFile(file)
     const id = crypto.randomUUID()
+    const kind = attachmentKindOrNull(normalizedFile)
     const base = {
       id,
-      type: policy ? KIND_TO_ATTACHMENT_TYPE[policy.kind] : ("file" as const),
-      name: file.name,
-      contentType: file.type,
-      file,
+      type: kind ? KIND_TO_ATTACHMENT_TYPE[kind] : ("file" as const),
+      name: normalizedFile.name,
+      contentType: normalizedFile.type,
+      file: normalizedFile,
     }
-
     const fail = (message: string): PendingAttachment => {
       toast.error(message)
       return { ...base, status: { type: "incomplete", reason: "error" } }
     }
-
-    if (!policy) {
-      yield fail(`不支持的文件类型：${file.type || "未知"}`)
-      return
-    }
-    if (file.size > policy.maxBytes) {
-      yield fail(
-        `文件超过大小上限（${Math.floor(policy.maxBytes / (1024 * 1024))}MB）`
-      )
+    try {
+      validateAttachmentFile(normalizedFile)
+    } catch (error) {
+      yield fail(error instanceof Error ? error.message : "附件校验失败")
       return
     }
 
     const channel = createProgressChannel()
-    const upload = uploadAndIngest(file, channel.push).finally(channel.close)
+    const upload = uploadAttachment(normalizedFile, { onProgress: channel.push })
+      .then(({ serverId }) => ({ serverId }))
+      .finally(channel.close)
     uploads.set(id, upload)
     // send() 之前无人 await 时，避免上传失败变成 unhandled rejection
     upload.catch(() => {})
@@ -219,9 +168,7 @@ export const r2AttachmentAdapter: AttachmentAdapter = {
       ?.then((r) => r.serverId)
       .catch(() => undefined)
     if (serverId) {
-      await fetch(`/api/attachments/${serverId}`, { method: "DELETE" }).catch(
-        () => {}
-      )
+      await deleteUploadedAttachment(serverId).catch(() => {})
     }
   },
 }
diff --git a/lib/chat/attachment-content-resolver.ts b/lib/chat/attachment-content-resolver.ts
index cb561e05..7fee1959 100644
--- a/lib/chat/attachment-content-resolver.ts
+++ b/lib/chat/attachment-content-resolver.ts
@@ -5,6 +5,7 @@ import { db } from "@/lib/db"
 import { attachments } from "@/lib/db/schema"
 import { hasChunks, retrieveChunks } from "@/lib/chat/retrieve"
 import type { ProjectFileRow } from "@/lib/thread-chat/persistence/mappers"
+import { getObjectBytes } from "@/lib/storage/r2"
 
 export type AttachmentRow = typeof attachments.$inferSelect
 export type AttachmentRenderMode = "full" | "retrieval" | "fallback"
@@ -132,6 +133,37 @@ export async function renderPdfAttachment(
   }
 }
 
+export async function renderTextAttachment(
+  row: AttachmentRow,
+  charBudget: number,
+  readBytes: (key: string) => Promise<Uint8Array> = getObjectBytes
+): Promise<{ text: string; mode: AttachmentRenderMode }> {
+  try {
+    const content = new TextDecoder("utf-8", { fatal: true }).decode(
+      await readBytes(row.key)
+    )
+    const truncated = content.length > charBudget
+    const body = truncated ? content.slice(0, charBudget) : content
+    return {
+      mode: truncated ? "fallback" : "full",
+      text:
+        `<attachment name="${escapeAttachmentAttribute(row.filename)}" mime="text/plain">\n` +
+        `${body}${truncated ? "\n\n[已截断：附件正文超出本轮上下文预算]" : ""}\n</attachment>`,
+    }
+  } catch (error) {
+    const reason =
+      error instanceof TypeError
+        ? "内容不是有效的 UTF-8 文本"
+        : "读取或解码失败"
+    return {
+      mode: "fallback",
+      text:
+        `<attachment name="${escapeAttachmentAttribute(row.filename)}" mime="text/plain">\n` +
+        `[文本附件解析失败：${reason}]\n</attachment>`,
+    }
+  }
+}
+
 export function attachmentPlaceholder(
   part: AttachmentFilePart,
   row?: AttachmentRow
diff --git a/lib/chat/attachment-context-policy.ts b/lib/chat/attachment-context-policy.ts
index 41665a82..75ed6bec 100644
--- a/lib/chat/attachment-context-policy.ts
+++ b/lib/chat/attachment-context-policy.ts
@@ -11,13 +11,16 @@ export interface AttachmentCandidatePlan<T extends AttachmentContextCandidate> {
   ordered: T[]
 }
 
-function readablePdf<T extends AttachmentContextCandidate>(row: T | undefined): row is T {
+function readableAttachment<T extends AttachmentContextCandidate>(
+  row: T | undefined
+): row is T {
   return Boolean(
     row &&
       row.status === "ready" &&
-      row.mimeType === "application/pdf" &&
-      row.pages &&
-      row.pages.length > 0
+      (row.mimeType === "text/plain" ||
+        (row.mimeType === "application/pdf" &&
+          row.pages &&
+          row.pages.length > 0))
   )
 }
 
@@ -37,12 +40,12 @@ export function planAttachmentCandidates<T extends AttachmentContextCandidate>({
   const explicitSet = new Set(explicitIds)
   const explicit = explicitIds.flatMap((id) => {
     const row = rowById.get(id)
-    return readablePdf(row) ? [row] : []
+    return readableAttachment(row) ? [row] : []
   })
   const project = projectIds.flatMap((id) => {
     if (explicitSet.has(id)) return []
     const row = rowById.get(id)
-    return readablePdf(row) ? [row] : []
+    return readableAttachment(row) ? [row] : []
   })
   return { explicit, project, ordered: [...explicit, ...project] }
 }
diff --git a/lib/chat/resolve-attachments.ts b/lib/chat/resolve-attachments.ts
index fa6ef5ba..adf01807 100644
--- a/lib/chat/resolve-attachments.ts
+++ b/lib/chat/resolve-attachments.ts
@@ -1,4 +1,5 @@
-import type { UIMessage } from "ai"
+import type { ModelMessage, UIMessage } from "ai"
+import { getObjectBytes } from "@/lib/storage/r2"
 import { PROJECT_FILE_CONTEXT_CHAR_BUDGET } from "@/constants/project-workspace"
 import {
   attachmentIdFromUrl,
@@ -6,6 +7,7 @@ import {
   loadOwnedAttachmentRows,
   projectFileManifestLine,
   renderPdfAttachment,
+  renderTextAttachment,
   type AttachmentFilePart,
   type AttachmentRenderMode,
   type AttachmentTextPart,
@@ -26,8 +28,16 @@ export interface ProjectFileContextStats {
   mode: "none" | AttachmentRenderMode | "mixed"
 }
 
+export interface ImageFileMaterialization {
+  markerUrl: string
+  mediaType: "image/png" | "image/jpeg" | "image/webp"
+  filename?: string
+  bytes: Uint8Array
+}
+
 export interface ResolvedAttachmentContext {
   messages: UIMessage[]
+  imageFiles: ImageFileMaterialization[]
   projectContext: string | null
   projectFileIds: string[]
   stats: ProjectFileContextStats
@@ -37,6 +47,51 @@ function isFilePart(part: { type: string }): part is AttachmentFilePart {
   return part.type === "file"
 }
 
+function isSupportedImageMimeType(
+  mediaType: string
+): mediaType is ImageFileMaterialization["mediaType"] {
+  return (
+    mediaType === "image/png" ||
+    mediaType === "image/jpeg" ||
+    mediaType === "image/webp"
+  )
+}
+
+export function applyImageFileMaterializations(
+  messages: ModelMessage[],
+  imageFiles: readonly ImageFileMaterialization[]
+): ModelMessage[] {
+  const byUrl = new Map(imageFiles.map((image) => [image.markerUrl, image]))
+  return messages.map((message) => {
+    if (message.role !== "user" || !Array.isArray(message.content)) return message
+    return {
+      ...message,
+      content: message.content.map((part) => {
+        const data = part.type === "file" ? part.data : null
+        if (
+          typeof data !== "object" ||
+          data === null ||
+          !("type" in data) ||
+          data.type !== "url" ||
+          !("url" in data) ||
+          !(data.url instanceof URL)
+        ) {
+          return part
+        }
+        const image = byUrl.get(data.url.toString())
+        return image
+          ? {
+              type: "file" as const,
+              mediaType: image.mediaType,
+              ...(image.filename ? { filename: image.filename } : {}),
+              data: { type: "data" as const, data: image.bytes },
+            }
+          : part
+      }),
+    }
+  })
+}
+
 function latestUserQuery(messages: UIMessage[]): string {
   for (let index = messages.length - 1; index >= 0; index -= 1) {
     if (messages[index].role !== "user") continue
@@ -66,10 +121,16 @@ export async function resolveAttachmentContext({
   messages,
   userId,
   projectFiles = [],
+  supportsImageInput = false,
+  readObjectBytes = getObjectBytes,
+  loadRows = loadOwnedAttachmentRows,
 }: {
   messages: UIMessage[]
   userId: string
   projectFiles?: ProjectFileRow[]
+  supportsImageInput?: boolean
+  readObjectBytes?: (key: string) => Promise<Uint8Array>
+  loadRows?: typeof loadOwnedAttachmentRows
 }): Promise<ResolvedAttachmentContext> {
   const explicitIds: string[] = []
   const seenExplicit = new Set<string>()
@@ -85,10 +146,7 @@ export async function resolveAttachmentContext({
   }
 
   const projectIds = projectFiles.map((row) => row.attachment.id)
-  const rowById = await loadOwnedAttachmentRows(userId, [
-    ...explicitIds,
-    ...projectIds,
-  ])
+  const rowById = await loadRows(userId, [...explicitIds, ...projectIds])
   const query = latestUserQuery(messages)
   const candidates = planAttachmentCandidates({
     explicitIds,
@@ -106,26 +164,46 @@ export async function resolveAttachmentContext({
       remainingBudget,
       candidates.length - index
     )
-    const result = await renderPdfAttachment(candidates[index], allocation, query)
+    const candidate = candidates[index]
+    const result =
+      candidate.mimeType === "text/plain"
+        ? await renderTextAttachment(candidate, allocation)
+        : await renderPdfAttachment(candidate, allocation, query)
     rendered.set(candidates[index].id, result)
     remainingBudget = Math.max(0, remainingBudget - result.text.length)
   }
 
-  const resolvedMessages = await Promise.all(
+  const imageFiles: ImageFileMaterialization[] = []
+  const resolvedMessages = (await Promise.all(
     messages.map(async (message) => ({
       ...message,
       parts: await Promise.all(
-        message.parts.map((part) => {
-          if (!isFilePart(part)) return Promise.resolve(part)
+        message.parts.map(async (part) => {
+          if (!isFilePart(part)) return part
           const id = attachmentIdFromUrl(part.url)
           const row = id ? rowById.get(id) : undefined
+          if (
+            supportsImageInput &&
+            row?.status === "ready" &&
+            isSupportedImageMimeType(part.mediaType) &&
+            row.mimeType === part.mediaType
+          ) {
+            const markerUrl = `https://attachment.invalid/${id}`
+            imageFiles.push({
+              markerUrl,
+              mediaType: part.mediaType,
+              ...(part.filename ? { filename: part.filename } : {}),
+              bytes: await readObjectBytes(row.key),
+            })
+            return { ...part, url: markerUrl }
+          }
           const resolved = id ? rendered.get(id) : undefined
-          if (resolved) return Promise.resolve({ type: "text", text: resolved.text })
-          return Promise.resolve(attachmentPlaceholder(part, row))
+          if (resolved) return { type: "text", text: resolved.text }
+          return attachmentPlaceholder(part, row)
         })
       ),
     }))
-  ) as UIMessage[]
+  )) as UIMessage[]
 
   const projectModes: AttachmentRenderMode[] = []
   const selectedContents: string[] = []
@@ -158,6 +236,7 @@ export async function resolveAttachmentContext({
 
   return {
     messages: resolvedMessages,
+    imageFiles,
     projectContext,
     projectFileIds: projectIds,
     stats: {
diff --git a/lib/storage/r2.ts b/lib/storage/r2.ts
index 27fbf240..77e6052c 100644
--- a/lib/storage/r2.ts
+++ b/lib/storage/r2.ts
@@ -60,10 +60,19 @@ export async function presignUpload(key: string, contentType: string) {
 }
 
 /** 签发短时效读取链接（私有桶的唯一读取入口） */
-export async function presignDownload(key: string) {
+export async function presignDownload(key: string, filename?: string) {
+  const contentDisposition = filename
+    ? `attachment; filename*=UTF-8''${encodeURIComponent(filename).replaceAll("'", "%27")}`
+    : undefined
   return getSignedUrl(
     getClient(),
-    new GetObjectCommand({ Bucket: bucket(), Key: key }),
+    new GetObjectCommand({
+      Bucket: bucket(),
+      Key: key,
+      ...(contentDisposition
+        ? { ResponseContentDisposition: contentDisposition }
+        : {}),
+    }),
     {
       expiresIn: DOWNLOAD_URL_TTL_SECONDS,
     }
diff --git a/lib/thread-chat/application/command-utils.ts b/lib/thread-chat/application/command-utils.ts
index c2d51d5f..37b61e72 100644
--- a/lib/thread-chat/application/command-utils.ts
+++ b/lib/thread-chat/application/command-utils.ts
@@ -1,7 +1,16 @@
 import { and, eq, inArray, isNull } from "drizzle-orm"
 import { attachments, messages, projects, threads } from "@/lib/db/schema"
-import { ATTACHMENT_URL_PREFIX } from "@/constants/attachment"
-import { isThreadChatModelId } from "@/constants/model"
+import {
+  ATTACHMENT_URL_PREFIX,
+  IMAGE_ATTACHMENT_LIMITS,
+  IMAGE_ATTACHMENT_MIME_TYPES,
+  IMAGE_MODEL_VALIDATION_MESSAGE,
+} from "@/constants/attachment"
+
+import {
+  isThreadChatModelId,
+  supportsModelImageInput,
+} from "@/constants/model"
 import type { ThreadChatUIMessage } from "@/lib/thread-chat/contracts/ui-message"
 import type { ConversationTransaction } from "@/lib/thread-chat/persistence/transaction"
 import { persistentMessageParts } from "@/lib/thread-chat/persistence/message-parts"
@@ -10,6 +19,23 @@ import {
   stateConflict,
 } from "@/lib/thread-chat/application/errors"
 
+export const THREAD_MESSAGE_ATTACHMENT_MIME_TYPES = [
+  "text/plain",
+  "image/png",
+  "image/jpeg",
+  "image/webp",
+] as const
+
+const THREAD_MESSAGE_ATTACHMENT_MIME_TYPE_SET = new Set<string>(
+  THREAD_MESSAGE_ATTACHMENT_MIME_TYPES
+)
+
+export { IMAGE_ATTACHMENT_MIME_TYPES }
+
+const IMAGE_ATTACHMENT_MIME_TYPE_SET = new Set<string>(
+  IMAGE_ATTACHMENT_MIME_TYPES
+)
+
 export interface FileReference {
   url: string
   mediaType: string
@@ -25,6 +51,34 @@ export function assertAllowedModel(modelId: string): void {
   }
 }
 
+export function hasImageFileReferences(
+  files: readonly FileReference[]
+): boolean {
+  return files.some((file) => IMAGE_ATTACHMENT_MIME_TYPE_SET.has(file.mediaType))
+}
+
+/** 必须在创建生成消息及进入付费模型调用前执行。 */
+export function assertModelSupportsNewAttachments(
+  modelId: string,
+  files: readonly FileReference[]
+): void {
+  const imageCount = files.filter((file) =>
+    IMAGE_ATTACHMENT_MIME_TYPE_SET.has(file.mediaType)
+  ).length
+  if (imageCount > IMAGE_ATTACHMENT_LIMITS.maxFilesPerMessage) {
+    throw new ConversationApplicationError(
+      "VALIDATION_ERROR",
+      `单次最多添加 ${IMAGE_ATTACHMENT_LIMITS.maxFilesPerMessage} 张图片`
+    )
+  }
+  if (imageCount > 0 && !supportsModelImageInput(modelId)) {
+    throw new ConversationApplicationError(
+      "VALIDATION_ERROR",
+      IMAGE_MODEL_VALIDATION_MESSAGE
+    )
+  }
+}
+
 function attachmentIdFromUrl(url: string): string | null {
   if (!url.startsWith(ATTACHMENT_URL_PREFIX)) return null
   const id = url.slice(ATTACHMENT_URL_PREFIX.length)
@@ -44,8 +98,18 @@ export async function assertOwnedReadyAttachments(
       "附件 URL 不合法"
     )
   }
+  if (
+    files.some(
+      (file) => !THREAD_MESSAGE_ATTACHMENT_MIME_TYPE_SET.has(file.mediaType)
+    )
+  ) {
+    throw new ConversationApplicationError(
+      "VALIDATION_ERROR",
+      "附件类型不允许用于 Thread 消息"
+    )
+  }
   const rows = await tx
-    .select({ id: attachments.id })
+    .select({ id: attachments.id, mimeType: attachments.mimeType })
     .from(attachments)
     .where(
       and(
@@ -57,6 +121,17 @@ export async function assertOwnedReadyAttachments(
   if (new Set(rows.map((row) => row.id)).size !== new Set(ids).size) {
     throw new ConversationApplicationError("NOT_FOUND", "附件不存在")
   }
+  const mimeTypeById = new Map(rows.map((row) => [row.id, row.mimeType]))
+  if (
+    files.some(
+      (file, index) => mimeTypeById.get(ids[index] as string) !== file.mediaType
+    )
+  ) {
+    throw new ConversationApplicationError(
+      "VALIDATION_ERROR",
+      "附件 mediaType 与服务端记录不一致"
+    )
+  }
 }
 
 export function buildUserParts(
diff --git a/lib/thread-chat/application/compile-model-context.ts b/lib/thread-chat/application/compile-model-context.ts
index 47a8709a..d0477f76 100644
--- a/lib/thread-chat/application/compile-model-context.ts
+++ b/lib/thread-chat/application/compile-model-context.ts
@@ -1,11 +1,16 @@
 import { convertToModelMessages, type ModelMessage } from "ai"
 import { db } from "@/lib/db"
 import { INHERITED_CHAR_BUDGET } from "@/constants/thread-chat"
+import { supportsModelImageInput } from "@/constants/model"
 import {
+  applyImageFileMaterializations,
   resolveAttachmentContext,
   type ProjectFileContextStats,
 } from "@/lib/chat/resolve-attachments"
-import type { ThreadChatUIMessage } from "@/lib/thread-chat/contracts/ui-message"
+import {
+  textFromMessageParts,
+  type ThreadChatUIMessage,
+} from "@/lib/thread-chat/contracts/ui-message"
 import {
   applyInheritedBudget,
   omittedNoticeText,
@@ -20,15 +25,7 @@ import { listProjectFileRows } from "@/lib/thread-chat/persistence/project-file-
 import { findOwnedThread } from "@/lib/thread-chat/persistence/thread-repository"
 
 function messageText(message: ThreadChatUIMessage): string {
-  return message.parts
-    .filter(
-      (
-        part
-      ): part is Extract<(typeof message.parts)[number], { type: "text" }> =>
-        part.type === "text"
-    )
-    .map((part) => part.text)
-    .join("\n")
+  return textFromMessageParts(message.parts, "\n")
 }
 
 function asUiMessage(row: {
@@ -54,10 +51,12 @@ export interface CompiledModelContext {
 export async function compileModelContextWithProject({
   userId,
   threadId,
+  modelId,
   excludeAssistantMessageId,
 }: {
   userId: string
   threadId: string
+  modelId: string
   excludeAssistantMessageId?: string
 }): Promise<CompiledModelContext> {
   const thread = await findOwnedThread(db, userId, threadId)
@@ -117,6 +116,7 @@ export async function compileModelContextWithProject({
     messages: uiMessages,
     userId,
     projectFiles,
+    supportsImageInput: supportsModelImageInput(modelId),
   })
   const withProjectContext: ThreadChatUIMessage[] = [
     ...(resolved.projectContext
@@ -156,7 +156,7 @@ export async function compileModelContextWithProject({
     },
   })
   return {
-    messages: modelMessages,
+    messages: applyImageFileMaterializations(modelMessages, resolved.imageFiles),
     projectFileIds: resolved.projectFileIds,
     projectFileStats: resolved.stats,
   }
@@ -166,6 +166,7 @@ export async function compileModelContextWithProject({
 export async function compileModelContext(input: {
   userId: string
   threadId: string
+  modelId: string
   excludeAssistantMessageId?: string
 }): Promise<ModelMessage[]> {
   return (await compileModelContextWithProject(input)).messages
diff --git a/lib/thread-chat/application/edit-turn.ts b/lib/thread-chat/application/edit-turn.ts
index 4dd04508..8e1e0a16 100644
--- a/lib/thread-chat/application/edit-turn.ts
+++ b/lib/thread-chat/application/edit-turn.ts
@@ -6,6 +6,7 @@ import { latestTurn } from "@/lib/thread-chat/domain/timeline"
 import {
   assertAllowedModel,
   assertOwnedReadyAttachments,
+  assertModelSupportsNewAttachments,
   buildUserParts,
   touchProjectAndThread,
 } from "@/lib/thread-chat/application/command-utils"
@@ -67,6 +68,7 @@ export function editLatestTurn(
         if (turn?.userMessage.id !== source.id) {
           stateConflict("只能编辑最新一轮用户消息")
         }
+        assertModelSupportsNewAttachments(command.modelId, command.files)
         await assertOwnedReadyAttachments(tx, userId, command.files)
         const [userSequence, assistantSequence] = await allocateThreadSequences(
           tx,
diff --git a/lib/thread-chat/application/fork-thread.ts b/lib/thread-chat/application/fork-thread.ts
index 407279bb..5e38920f 100644
--- a/lib/thread-chat/application/fork-thread.ts
+++ b/lib/thread-chat/application/fork-thread.ts
@@ -8,6 +8,7 @@ import { buildFrozenForkContext } from "@/lib/thread-chat/domain/fork-context"
 import {
   assertAllowedModel,
   assertOwnedReadyAttachments,
+  assertModelSupportsNewAttachments,
   buildUserParts,
   touchProjectAndThread,
 } from "@/lib/thread-chat/application/command-utils"
@@ -93,6 +94,7 @@ export function forkThread(
           await touchProjectAndThread(tx, project.id, child.id)
           return { thread: toThreadDTO(child), generation: null }
         }
+        assertModelSupportsNewAttachments(command.modelId, command.firstTurn.files)
         await assertOwnedReadyAttachments(tx, userId, command.firstTurn.files)
         const [userSequence, assistantSequence] = await allocateThreadSequences(
           tx,
diff --git a/lib/thread-chat/application/send-message.ts b/lib/thread-chat/application/send-message.ts
index 5f351ffa..4fcc43df 100644
--- a/lib/thread-chat/application/send-message.ts
+++ b/lib/thread-chat/application/send-message.ts
@@ -4,6 +4,7 @@ import type { GenerationAcceptedDTO } from "@/lib/thread-chat/contracts/dto"
 import {
   assertAllowedModel,
   assertOwnedReadyAttachments,
+  assertModelSupportsNewAttachments,
   assertThreadReadyForTurn,
   buildUserParts,
   touchProjectAndThread,
@@ -46,6 +47,7 @@ export function sendMessage(
         if (!project) notFound()
         if (project.archivedAt) stateConflict("已归档 Project 不可发送消息")
         await assertThreadReadyForTurn(tx, project.id, thread.id)
+        assertModelSupportsNewAttachments(command.modelId, command.files)
         await assertOwnedReadyAttachments(tx, userId, command.files)
         const [userSequence, assistantSequence] = await allocateThreadSequences(
           tx,
diff --git a/lib/thread-chat/application/start-project.ts b/lib/thread-chat/application/start-project.ts
index 4c4c3345..f6c12461 100644
--- a/lib/thread-chat/application/start-project.ts
+++ b/lib/thread-chat/application/start-project.ts
@@ -5,6 +5,7 @@ import type { GenerationAcceptedDTO } from "@/lib/thread-chat/contracts/dto"
 import {
   assertAllowedModel,
   assertOwnedReadyAttachments,
+  assertModelSupportsNewAttachments,
   buildUserParts,
 } from "@/lib/thread-chat/application/command-utils"
 import { notFound, stateConflict } from "@/lib/thread-chat/application/errors"
@@ -39,6 +40,7 @@ export function startProject(userId: string, command: StartProjectCommand) {
           if (existing.userId !== userId) notFound()
           stateConflict("Project 已存在")
         }
+        assertModelSupportsNewAttachments(command.modelId, command.files)
         await assertOwnedReadyAttachments(tx, userId, command.files)
         const now = new Date()
         const [project] = await tx
diff --git a/lib/thread-chat/contracts/ui-message.ts b/lib/thread-chat/contracts/ui-message.ts
index 2f568c43..9f785be0 100644
--- a/lib/thread-chat/contracts/ui-message.ts
+++ b/lib/thread-chat/contracts/ui-message.ts
@@ -68,6 +68,15 @@ export type ThreadChatUIMessageChunk = UIMessageChunk<
   ThreadChatDataParts
 >
 
+export function textFromMessageParts(
+  parts: ThreadChatUIMessage["parts"],
+  separator = ""
+): string {
+  return parts
+    .flatMap((part) => (part.type === "text" ? [part.text] : []))
+    .join(separator)
+}
+
 export function isThreadChatUIMessage(
   value: unknown
 ): value is ThreadChatUIMessage {
diff --git a/lib/thread-chat/streaming/run-generation.ts b/lib/thread-chat/streaming/run-generation.ts
index 0d88167d..ddf8b085 100644
--- a/lib/thread-chat/streaming/run-generation.ts
+++ b/lib/thread-chat/streaming/run-generation.ts
@@ -133,6 +133,7 @@ async function runGenerationCore({
   const compiledContext = await compileModelContextWithProject({
     userId,
     threadId: thread.id,
+    modelId: message.modelId,
     excludeAssistantMessageId: message.id,
   })
   const prepare = dependencies.prepare ?? prepareGeneration