fix(ui): open saved plans against their owning project

Saved Project knowledge plans opened as an empty editor whenever the
viewer could not resolve the owning project from the current directory:
managed chats (openchamber:chats is not a registered project), worktrees
outside the repo path, and plan tabs restored after a reload. Titles
still rendered because the list reads the manifest through the correct
owner.

- Thread the owner explicitly (savedProjectPlan = { projectRef, planId })
  from the panel, mobile surfaces, and persisted context tabs; PlanView
  no longer guesses the project.
- An unrecognized directory resolves to no owner instead of borrowing
  the active project's knowledge.
- Serialize plan writes per document (planSaveQueue) so close/switch
  within the autosave debounce no longer drops the last edits, saves
  cannot land out of order, and a recovered save clears the error banner.
- Send saved-plan contents inline in Improve/Implement prompts (they
  have no file path); disable those actions for managed-chat plans,
  which have no project directory to create a session in.
- Drop persisted plan tabs that carry an id without an owner rather than
  reopening them against a guessed project.

packages/ui/src/lib/planSaveQueue.test.ts

@@ -0,0 +1,142 @@
+import { describe, expect, test } from 'bun:test';
+
+import { createPlanSaveQueue } from './planSaveQueue';
+
+type Deferred = { promise: Promise<void>; resolve: () => void; reject: () => void };
+
+const deferred = (): Deferred => {
+  let resolve!: () => void;
+  let reject!: () => void;
+  const promise = new Promise<void>((res, rej) => {
+    resolve = res;
+    reject = rej;
+  });
+  return { promise, resolve, reject };
+};
+
+describe('planSaveQueue', () => {
+  test('runs writes for one document in schedule order even when they resolve out of order', async () => {
+    const queue = createPlanSaveQueue();
+    const order: string[] = [];
+    const first = deferred();
+    const second = deferred();
+
+    const firstDone = queue.schedule('doc', 1, async () => {
+      await first.promise;
+      order.push('first');
+    });
+    const secondDone = queue.schedule('doc', 2, async () => {
+      order.push('second');
+    });
+
+    // Second started only after first settles, regardless of timing.
+    first.resolve();
+    await firstDone;
+    second.resolve();
+    await secondDone;
+
+    expect(order).toEqual(['first', 'second']);
+  });
+
+  test('skips a revision at or below the last queued revision for the same document', async () => {
+    const queue = createPlanSaveQueue();
+    let writes = 0;
+
+    await queue.schedule('doc', 3, async () => {
+      writes += 1;
+    });
+    await queue.schedule('doc', 3, async () => {
+      writes += 1;
+    });
+    await queue.schedule('doc', 2, async () => {
+      writes += 1;
+    });
+
+    expect(writes).toBe(1);
+  });
+
+  test('never lets a write for one document block another document', async () => {
+    const queue = createPlanSaveQueue();
+    const blocked = deferred();
+
+    const blockedDone = queue.schedule('a', 1, async () => {
+      await blocked.promise;
+    });
+    let otherRan = false;
+    await queue.schedule('b', 1, async () => {
+      otherRan = true;
+    });
+
+    expect(otherRan).toBe(true);
+    blocked.resolve();
+    await blockedDone;
+  });
+
+  test('pendingFor waits for the outstanding chain of that document only', async () => {
+    const queue = createPlanSaveQueue();
+    const slow = deferred();
+    let slowSettled = false;
+
+    void queue.schedule('a', 1, async () => {
+      await slow.promise;
+      slowSettled = true;
+    });
+    await queue.schedule('b', 1, async () => {});
+
+    await queue.pendingFor('b');
+    expect(slowSettled).toBe(false);
+
+    slow.resolve();
+    await queue.pendingFor('a');
+    expect(slowSettled).toBe(true);
+  });
+
+  test('reset clears the revision watermark so a reloaded document can save again', async () => {
+    const queue = createPlanSaveQueue();
+    let writes = 0;
+
+    await queue.schedule('doc', 5, async () => {
+      writes += 1;
+    });
+    queue.reset('doc');
+    await queue.schedule('doc', 1, async () => {
+      writes += 1;
+    });
+
+    expect(writes).toBe(2);
+  });
+
+  test('a failed write does not poison the chain for later writes', async () => {
+    const queue = createPlanSaveQueue();
+
+    const failing = queue.schedule('doc', 1, async () => {
+      throw new Error('write failed');
+    });
+    let secondRan = false;
+    const second = queue.schedule('doc', 2, async () => {
+      secondRan = true;
+    });
+
+    await expect(failing).rejects.toThrow('write failed');
+    await second;
+    expect(secondRan).toBe(true);
+    await queue.pendingFor('doc');
+  });
+
+  test('allows the same revision to retry after its write fails', async () => {
+    const queue = createPlanSaveQueue();
+    let attempts = 0;
+
+    const failing = queue.schedule('doc', 1, async () => {
+      attempts += 1;
+      throw new Error('write failed');
+    });
+    await expect(failing).rejects.toThrow('write failed');
+
+    await queue.schedule('doc', 1, async () => {
+      attempts += 1;
+    });
+
+    expect(attempts).toBe(2);
+  });
+});

packages/ui/src/lib/planSaveQueue.ts

@@ -0,0 +1,61 @@
+/**
+ * Write queue for open plan documents.
+ *
+ * Debounced autosave and close-time flushes must reach the disk in edit order,
+ * and a document re-opened while its own write is still in flight must read
+ * the post-write state, not race it. The queue serializes writes per logical
+ * document key and deduplicates revisions so a flush of revision N can never
+ * run behind, or twice behind, a debounced save of the same revision.
+ */
+
+interface PlanSaveQueue {
+  /**
+   * Queue one write for `key`. Writes for the same key run in schedule order;
+   * writes for different keys never block each other. A revision at or below
+   * the last queued revision for that key is skipped — the queued write
+   * already carries newer content — and the returned promise tracks the
+   * outstanding chain so callers can still await it.
+   */
+  schedule: (key: string, revision: number, write: () => Promise<void>) => Promise<void>;
+  /** Resolves when every write queued for `key` has settled. */
+  pendingFor: (key: string) => Promise<void>;
+  /**
+   * Forgets the revision watermark for `key`. Call when a document is freshly
+   * loaded: its revision counter restarts, and stale watermarks from a
+   * previous open must not swallow the first real edit.
+   */
+  reset: (key: string) => void;
+}
+
+export const createPlanSaveQueue = (): PlanSaveQueue => {
+  const chains = new Map<string, Promise<void>>();
+  const lastRevision = new Map<string, number>();
+
+  return {
+    schedule: (key, revision, write) => {
+      if (revision <= (lastRevision.get(key) ?? Number.NEGATIVE_INFINITY)) {
+        return chains.get(key) ?? Promise.resolve();
+      }
+      lastRevision.set(key, revision);
+      const previous = chains.get(key) ?? Promise.resolve();
+      // A failed write must not poison the chain: the next write for this
+      // document is still safe to attempt, and error surfacing belongs to the
+      // caller that owns UI state.
+      const next = previous.then(write, write);
+      chains.set(key, next.catch(() => {
+        // Keep newer queued revisions deduplicated, but let the caller retry
+        // this exact revision after its write has failed.
+        if (lastRevision.get(key) === revision) {
+          lastRevision.delete(key);
+        }
+      }));
+      return next;
+    },
+    pendingFor: async (key) => {
+      await chains.get(key);
+    },
+    reset: (key) => {
+      lastRevision.delete(key);
+    },
+  };
+};

packages/ui/src/lib/projectContextApi.ts

@@ -57,6 +57,17 @@ export interface ProjectRef {
   path: string;
 }
 
+/**
+ * A saved project plan plus the project that owns it, carried as one value so
+ * a viewer can never end up with a plan id whose owner it has to guess.
+ * PlanView resolves no owner on its own: the panel (or the persisted tab,
+ * or the mobile surface) that opened the plan knows the owner exactly.
+ */
+export interface SavedProjectPlanTarget {
+  projectRef: ProjectRef;
+  planId: string;
+}
+
 export const PROJECT_NOTE_BODY_MAX_LENGTH = 3000;
 export const PROJECT_TODO_TEXT_MAX_LENGTH = 120;