diff --git a/src/tools/docShared.ts b/src/tools/docShared.ts
index 2811b9d..c97409d 100644
--- a/src/tools/docShared.ts
+++ b/src/tools/docShared.ts
@@ -162,13 +162,29 @@ export async function nextDocOrder(
 export async function touchDocForEdit(
   docRef: DocumentReference,
   currentStatus: unknown,
+  change?: {
+    actor?: string;
+    action?: string;
+    blockId?: string;
+    summary?: string;
+  },
 ): Promise<void> {
+  const now = FieldValue.serverTimestamp();
   const patch: Record<string, unknown> = {
     revision: FieldValue.increment(1),
-    updatedAt: FieldValue.serverTimestamp(),
+    updatedAt: now,
   };
   if (currentStatus === "draft" || currentStatus == null) {
     patch.status = "under_discussion";
   }
-  await docRef.set(patch, { merge: true });
+  const batch = docRef.firestore.batch();
+  batch.set(docRef, patch, { merge: true });
+  batch.set(docRef.collection("revisions").doc(), {
+    actor: change?.actor ?? "agent",
+    action: change?.action ?? "doc_edited",
+    blockId: change?.blockId ?? null,
+    summary: change?.summary ?? null,
+    createdAt: now,
+  });
+  await batch.commit();
 }
diff --git a/src/tools/proposePlan.ts b/src/tools/proposePlan.ts
index 65c921e..64b8032 100644
--- a/src/tools/proposePlan.ts
+++ b/src/tools/proposePlan.ts
@@ -43,6 +43,14 @@ export const proposePlan: Tool<typeof InputSchema> = {
       };
     }
     const { docRef } = refs;
+    const current = await docRef.get();
+    if (current.data()?.status === "materialized") {
+      return {
+        ok: false,
+        errorClass: "BAD_INPUT",
+        message: "This plan is already approved and materialized; it cannot be proposed again.",
+      };
+    }
 
     const blocksSnap = await docRef.collection("blocks").get();
     let groups = 0;
@@ -85,6 +93,13 @@ export const proposePlan: Tool<typeof InputSchema> = {
     );
     await batch.commit();
 
+    await docRef.collection("revisions").doc().set({
+      actor: ctx.convId ?? "agent",
+      action: "plan_proposed",
+      summary: `Proposed ${tasks} task${tasks === 1 ? "" : "s"} across ${groups} group${groups === 1 ? "" : "s"}.`,
+      createdAt: FieldValue.serverTimestamp(),
+    });
+
     // Notify the team in THIS doc's discussion.
     await docRef.collection("messages").doc().set({
       from: "agent",
diff --git a/src/tools/upsertPlanGroup.ts b/src/tools/upsertPlanGroup.ts
index 6e322f7..3dd53ad 100644
--- a/src/tools/upsertPlanGroup.ts
+++ b/src/tools/upsertPlanGroup.ts
@@ -53,6 +53,13 @@ export const upsertPlanGroup: Tool<typeof InputSchema> = {
     const { docRef } = refs;
     const docSnap = await docRef.get();
     const status = (docSnap.data() as Record<string, unknown>)?.status;
+    if (status === "materialized") {
+      return {
+        ok: false,
+        errorClass: "BAD_INPUT",
+        message: "This plan is already materialized. Discuss changes in the doc instead of rewriting the approved task structure.",
+      };
+    }
 
     const blocksCol = docRef.collection("blocks");
     const groupRef = args.groupId
@@ -91,7 +98,12 @@ export const upsertPlanGroup: Tool<typeof InputSchema> = {
       { merge: true },
     );
 
-    await touchDocForEdit(docRef, status);
+    await touchDocForEdit(docRef, status, {
+      actor: ctx.convId,
+      action: existing && existing.exists ? "plan_group_updated" : "plan_group_created",
+      blockId: groupRef.id,
+      summary: args.title,
+    });
 
     return { ok: true, data: { docId: refs.docId, groupId: groupRef.id } };
   },
diff --git a/src/tools/upsertPlanTask.ts b/src/tools/upsertPlanTask.ts
index 7280855..0adf632 100644
--- a/src/tools/upsertPlanTask.ts
+++ b/src/tools/upsertPlanTask.ts
@@ -61,9 +61,32 @@ export const upsertPlanTask: Tool<typeof InputSchema> = {
     const { docRef } = refs;
     const docSnap = await docRef.get();
     const status = (docSnap.data() as Record<string, unknown>)?.status;
+    if (status === "materialized") {
+      return {
+        ok: false,
+        errorClass: "BAD_INPUT",
+        message: "This plan is already materialized. Do not add or rewrite approved tasks.",
+      };
+    }
 
     const blocksCol = docRef.collection("blocks");
 
+    if (args.suggestedAgent) {
+      const project = await docRef.parent.parent!.get();
+      const roster = Array.isArray(project.data()?.agentIds)
+        ? (project.data()?.agentIds as unknown[]).filter(
+            (name): name is string => typeof name === "string" && name.length > 0,
+          )
+        : [];
+      if (!roster.includes(args.suggestedAgent)) {
+        return {
+          ok: false,
+          errorClass: "BAD_INPUT",
+          message: `Unknown suggestedAgent "${args.suggestedAgent}". Use one of the project's exact agent names: ${roster.join(", ") || "(no agents assigned)"}.`,
+        };
+      }
+    }
+
     // The referenced group must exist and be a planGroup.
     const groupSnap = await blocksCol.doc(args.groupId).get();
     if (!groupSnap.exists || (groupSnap.data() as Record<string, unknown>).type !== "planGroup") {
@@ -111,7 +134,12 @@ export const upsertPlanTask: Tool<typeof InputSchema> = {
       { merge: true },
     );
 
-    await touchDocForEdit(docRef, status);
+    await touchDocForEdit(docRef, status, {
+      actor: ctx.convId,
+      action: existing && existing.exists ? "plan_task_updated" : "plan_task_created",
+      blockId: taskRef.id,
+      summary: args.title,
+    });
 
     return { ok: true, data: { docId: refs.docId, taskId: taskRef.id } };
   },