diff --git a/packages/cli/src/__tests__/pi-transcript.test.ts b/packages/cli/src/__tests__/pi-transcript.test.ts
index 49b3a51ce8..ecc6e599c2 100644
--- a/packages/cli/src/__tests__/pi-transcript.test.ts
+++ b/packages/cli/src/__tests__/pi-transcript.test.ts
@@ -54,6 +54,24 @@ function toolStatus(entry: MakaPiToolEntry | undefined): string | undefined {
 }
 
 describe('Maka Pi TUI transcript', () => {
+  test('renders provider dropping guidance from durable declaration state', () => {
+    const state = createMakaPiTranscriptState();
+    replaceTranscriptWithStoredMessages(state, [
+      {
+        type: 'system_note',
+        id: 'drop-1',
+        turnId: 't1',
+        ts: 1,
+        kind: 'context_provider_dropping',
+        data: { inputTokens: 100, priorInputTokens: 100, contextWindowDeclared: true },
+      },
+    ]);
+    assert.match(
+      renderMakaPiTranscript(state, meta(), 120).map(stripAnsi).join('\n'),
+      /already declared/,
+    );
+  });
+
   test('renders manual compaction from the typed terminal outcome', async () => {
     for (const [outcome, expected] of [
       [{ kind: 'compacted' as const, checkpointId: 'checkpoint-1' }, 'Context compacted.'],
diff --git a/packages/cli/src/pi-transcript.ts b/packages/cli/src/pi-transcript.ts
index d7af4da7df..3f2390db43 100644
--- a/packages/cli/src/pi-transcript.ts
+++ b/packages/cli/src/pi-transcript.ts
@@ -1355,14 +1355,24 @@ function systemNoteText(message: SystemNoteMessage): string | undefined {
       return 'Context summary failed; the session continued without a new summary.';
     case 'context_provider_dropping': {
       const data = message.data as
-        | { inputTokens?: unknown; priorInputTokens?: unknown }
+        | { inputTokens?: unknown; priorInputTokens?: unknown; contextWindowDeclared?: unknown }
         | undefined;
       const used = typeof data?.inputTokens === 'number' ? data.inputTokens : undefined;
       const prior = typeof data?.priorInputTokens === 'number' ? data.priorInputTokens : undefined;
-      if (used === undefined || prior === undefined) {
-        return 'The provider is dropping or rewriting context: content was appended but its reported usage did not grow. Declare a context window for this model so Maka compacts first.';
-      }
-      return `The provider is dropping or rewriting context: content was appended, and it counted ${used} input tokens against ${prior} before, which is no growth. Declare a context window for this model so Maka compacts first.`;
+      const declared =
+        typeof data?.contextWindowDeclared === 'boolean' ? data.contextWindowDeclared : undefined;
+      if (used === undefined || prior === undefined)
+        return declared === true
+          ? 'The provider is dropping or rewriting context, but a context window is already declared for this model; Maka will compact first.'
+          : declared === false
+            ? 'The provider is dropping or rewriting context: content was appended but its reported usage did not grow. Declare a context window for this model so Maka compacts first.'
+            : 'The provider is dropping or rewriting context: content was appended but its reported usage did not grow.';
+      const detail = `The provider is dropping or rewriting context: content was appended, and it counted ${used} input tokens against ${prior} before, which is no growth.`;
+      return declared === true
+        ? `${detail} A context window is already declared for this model, so Maka will compact first.`
+        : declared === false
+          ? `${detail} Declare a context window for this model so Maka compacts first.`
+          : detail;
     }
     case 'context_overflow_after_compaction':
       return 'History was compacted and the provider still called this request too large. What remains also carries the system prompt, the tool schemas, the summary and the recent tail; shortening this message is the part you control.';
diff --git a/packages/runtime/src/__tests__/mid-turn-capacity-backend.test.ts b/packages/runtime/src/__tests__/mid-turn-capacity-backend.test.ts
index a1f9df154b..34759106aa 100644
--- a/packages/runtime/src/__tests__/mid-turn-capacity-backend.test.ts
+++ b/packages/runtime/src/__tests__/mid-turn-capacity-backend.test.ts
@@ -1323,7 +1323,11 @@ function defineMidTurnSuite(consumer: ConsumerMode): void {
       (message): message is { type: 'system_note'; kind: string; data?: unknown } =>
         (message as { kind?: string }).kind === 'context_provider_dropping',
     );
-    assert.deepEqual(note?.data, { inputTokens: 3_716, priorInputTokens: 3_716 });
+    assert.deepEqual(note?.data, {
+      inputTokens: 3_716,
+      priorInputTokens: 3_716,
+      contextWindowDeclared: false,
+    });
   });
 
   test('does not report dropping across the boundary when the input grew', async () => {
@@ -1399,10 +1403,15 @@ function defineMidTurnSuite(consumer: ConsumerMode): void {
     await runFixtureTurn(fixture, consumer);
 
     const note = fixture.messages.find(
-      (message): message is { type: 'system_note'; kind: string } =>
+      (message): message is { type: 'system_note'; kind: string; data?: unknown } =>
         (message as { type?: string }).type === 'system_note',
     );
     assert.equal(note?.kind, 'context_provider_dropping');
+    assert.deepEqual(note?.data, {
+      inputTokens: 100,
+      priorInputTokens: 100,
+      contextWindowDeclared: true,
+    });
   });
 
   test('records provider context dropping only for an unshaped usage decrease', async () => {
@@ -1414,10 +1423,15 @@ function defineMidTurnSuite(consumer: ConsumerMode): void {
     await runFixtureTurn(fixture, consumer);
 
     const note = fixture.messages.find(
-      (message): message is { type: 'system_note'; kind: string } =>
+      (message): message is { type: 'system_note'; kind: string; data?: unknown } =>
         (message as { type?: string }).type === 'system_note',
     );
     assert.equal(note?.kind, 'context_provider_dropping');
+    assert.deepEqual(note?.data, {
+      inputTokens: 50,
+      priorInputTokens: 100,
+      contextWindowDeclared: true,
+    });
   });
 
   test('does not call provider context dropping when active pruning explains the decrease', async () => {
diff --git a/packages/runtime/src/ai-sdk-turn.ts b/packages/runtime/src/ai-sdk-turn.ts
index b9a436d850..bb9a7e3910 100644
--- a/packages/runtime/src/ai-sdk-turn.ts
+++ b/packages/runtime/src/ai-sdk-turn.ts
@@ -1734,6 +1734,7 @@ export class AiSdkTurn {
                     await this.recordSystemNote('context_provider_dropping', turnId, {
                       inputTokens: stepUsage.inputTokens,
                       priorInputTokens: priorInput,
+                      contextWindowDeclared: midTurnState.capacity !== undefined,
                     });
                   }
                   // Fail closed: reset on every step boundary so a missing final
diff --git a/packages/ui/src/__tests__/materialize.test.ts b/packages/ui/src/__tests__/materialize.test.ts
index 047e08f677..1576a49ac6 100644
--- a/packages/ui/src/__tests__/materialize.test.ts
+++ b/packages/ui/src/__tests__/materialize.test.ts
@@ -207,6 +207,23 @@ describe("steering timeline", () => {
 });
 
 describe("materializeChat message metadata", () => {
+  test("renders provider dropping guidance from durable declaration state", () => {
+    const base = {
+      type: "system_note" as const,
+      id: "drop",
+      turnId: "t1",
+      ts: 1,
+      kind: "context_provider_dropping" as const,
+      data: { inputTokens: 98_247, priorInputTokens: 124_832 },
+    };
+    const declared = materializeChat([{ ...base, data: { ...base.data, contextWindowDeclared: true } }], "en")[0]?.text;
+    const undeclared = materializeChat([{ ...base, data: { ...base.data, contextWindowDeclared: false } }], "en")[0]?.text;
+    const legacy = materializeChat([base], "en")[0]?.text;
+    assert.match(declared ?? "", /already declared/);
+    assert.match(undeclared ?? "", /Declare a context window/);
+    assert.doesNotMatch(legacy ?? "", /Declare a context window/);
+  });
+
   test("localizes visible system notes", () => {
     const messages: StoredMessage[] = [
       {
diff --git a/packages/ui/src/conversation-copy.ts b/packages/ui/src/conversation-copy.ts
index 1bf10a43b4..64b24211f7 100644
--- a/packages/ui/src/conversation-copy.ts
+++ b/packages/ui/src/conversation-copy.ts
@@ -329,7 +329,7 @@ export interface ConversationCopy {
       contextCompacting: string;
       contextCompacted: string;
       contextCompactionFailedOpen: string;
-      contextProviderDropping: (used: number, prior: number) => string;
+      contextProviderDropping: (used: number, prior: number, contextWindowDeclared?: boolean) => string;
       contextWindowSuggestion: (tokens: number, declared: number | undefined) => string;
       contextWindowOverrun: (used: number, declared: number) => string;
       contextReportedWindowExceeded: (used: number, reported: number) => string;
@@ -561,8 +561,11 @@ const CONVERSATION_COPY = {
         contextCompacting: '正在压缩上下文…',
         contextCompacted: '已压缩较早的上下文。',
         contextCompactionFailedOpen: '上下文压缩失败。',
-        contextProviderDropping: (used, prior) =>
-          `供应商在丢弃或改写上下文：追加了内容，它报告的输入却是 ${used.toLocaleString('zh-CN')} tokens，与之前的 ${prior.toLocaleString('zh-CN')} 相比没有增长。在连接设置里为该模型声明上下文窗口，让 Maka 先行压缩。`,
+        contextProviderDropping: (used, prior, declared) => declared === true
+          ? `供应商在丢弃或改写上下文：追加了内容，它报告的输入却是 ${used.toLocaleString('zh-CN')} tokens，与之前的 ${prior.toLocaleString('zh-CN')} 相比没有增长。该模型已声明上下文窗口，Maka 会先行压缩。`
+          : declared === false
+            ? `供应商在丢弃或改写上下文：追加了内容，它报告的输入却是 ${used.toLocaleString('zh-CN')} tokens，与之前的 ${prior.toLocaleString('zh-CN')} 相比没有增长。在连接设置里为该模型声明上下文窗口，让 Maka 先行压缩。`
+            : `供应商在丢弃或改写上下文：追加了内容，它报告的输入却是 ${used.toLocaleString('zh-CN')} tokens，与之前的 ${prior.toLocaleString('zh-CN')} 相比没有增长。`,
         contextWindowSuggestion: (tokens, declared) =>
           declared === undefined
             ? `供应商拒绝了这次请求。该模型未声明上下文窗口；上次成功的用量约 ${tokens} tokens，可将窗口设为该值让 Maka 先行压缩。`
@@ -724,8 +727,11 @@ const CONVERSATION_COPY = {
         contextCompacting: '正在壓縮上下文…',
         contextCompacted: '已壓縮較早的上下文。',
         contextCompactionFailedOpen: '上下文壓縮失敗。',
-        contextProviderDropping: (used, prior) =>
-          `供應商在丟棄或改寫上下文：追加了內容，它報告的輸入卻是 ${used.toLocaleString('zh-TW')} tokens，與之前的 ${prior.toLocaleString('zh-TW')} 相比沒有成長。在連線設定裡為該模型宣告上下文視窗，讓 Maka 先行壓縮。`,
+        contextProviderDropping: (used, prior, declared) => declared === true
+          ? `供應商在丟棄或改寫上下文：追加了內容，它報告的輸入卻是 ${used.toLocaleString('zh-TW')} tokens，與之前的 ${prior.toLocaleString('zh-TW')} 相比沒有成長。該模型已宣告上下文視窗，Maka 會先行壓縮。`
+          : declared === false
+            ? `供應商在丟棄或改寫上下文：追加了內容，它報告的輸入卻是 ${used.toLocaleString('zh-TW')} tokens，與之前的 ${prior.toLocaleString('zh-TW')} 相比沒有成長。在連線設定裡為該模型宣告上下文視窗，讓 Maka 先行壓縮。`
+            : `供應商在丟棄或改寫上下文：追加了內容，它報告的輸入卻是 ${used.toLocaleString('zh-TW')} tokens，與之前的 ${prior.toLocaleString('zh-TW')} 相比沒有成長。`,
         contextWindowSuggestion: (tokens, declared) =>
           declared === undefined
             ? `供應商拒絕了這次請求。該模型未宣告上下文視窗；上次成功的用量約 ${tokens} tokens，可將視窗設為該值讓 Maka 先行壓縮。`
@@ -913,8 +919,11 @@ const CONVERSATION_COPY = {
         contextCompacting: 'Compacting context…',
         contextCompacted: 'Earlier context compacted.',
         contextCompactionFailedOpen: 'Context compaction failed.',
-        contextProviderDropping: (used, prior) =>
-          `The provider is dropping or rewriting context: content was appended, and it counted ${used.toLocaleString('en-US')} input tokens against ${prior.toLocaleString('en-US')} before, which is no growth. Declare a context window for this model in the connection settings so Maka compacts first.`,
+        contextProviderDropping: (used, prior, declared) => declared === true
+          ? `The provider is dropping or rewriting context: content was appended, and it counted ${used.toLocaleString('en-US')} input tokens against ${prior.toLocaleString('en-US')} before, which is no growth. A context window is already declared for this model, so Maka will compact first.`
+          : declared === false
+            ? `The provider is dropping or rewriting context: content was appended, and it counted ${used.toLocaleString('en-US')} input tokens against ${prior.toLocaleString('en-US')} before, which is no growth. Declare a context window for this model in the connection settings so Maka compacts first.`
+            : `The provider is dropping or rewriting context: content was appended, and its reported input usage did not grow.`,
         contextWindowSuggestion: (tokens, declared) =>
           declared === undefined
             ? `The provider rejected this request. No context window is declared for this model; the last accepted usage was about ${tokens} tokens — set the window to that value so Maka compacts first.`
diff --git a/packages/ui/src/materialize.ts b/packages/ui/src/materialize.ts
index 23262feedb..4fa8e8567c 100644
--- a/packages/ui/src/materialize.ts
+++ b/packages/ui/src/materialize.ts
@@ -146,10 +146,11 @@ function systemNoteLabel(kind: string, data: unknown, locale: UiLocale): string
   if (kind === "context_compacted") return copy.contextCompacted;
   if (kind === "context_compaction_failed_open") return copy.contextCompactionFailedOpen;
   if (kind === "context_provider_dropping") {
-    const dropping = data as { inputTokens?: unknown; priorInputTokens?: unknown } | undefined;
+    const dropping = data as { inputTokens?: unknown; priorInputTokens?: unknown; contextWindowDeclared?: unknown } | undefined;
     const used = typeof dropping?.inputTokens === "number" ? dropping.inputTokens : 0;
     const prior = typeof dropping?.priorInputTokens === "number" ? dropping.priorInputTokens : 0;
-    return copy.contextProviderDropping(used, prior);
+    const declared = typeof dropping?.contextWindowDeclared === "boolean" ? dropping.contextWindowDeclared : undefined;
+    return copy.contextProviderDropping(used, prior, declared);
   }
   if (kind === "context_overflow_after_compaction") return copy.contextOverflowAfterCompaction;
   if (kind === "context_reported_window_exceeded") {