Fix a2a in_reply_to stamp: publish through outbound.db, not module state

The active batch's inReplyTo lived in module-level state in current-batch.ts,
but the nanoclaw MCP server runs as a separate stdio subprocess from the poll
loop, so getCurrentInReplyTo() always read null there. The a2a reply stamp was
therefore dead — only the host peer-affinity fallback kept replies routing.

Publish the stamp through session_state in outbound.db (both processes already
open it): the poll loop writes it at batch start and clears it in the existing
finally; the MCP tools read it with an updated_at staleness guard so a stamp
left behind by a killed container isn't reused. Delete current-batch.ts and
reseed core.test.ts via the DB so it reflects the real process boundary.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

container/agent-runner/src/current-batch.ts

@@ -1,29 +0,0 @@
-/**
- * Per-batch context the poll loop publishes for downstream consumers
- * (MCP tools, etc.) that don't sit on the poll-loop's call stack.
- *
- * Today the only field is `inReplyTo` — the id of the first inbound
- * message in the batch the agent is currently processing. MCP tools like
- * `send_message` and `send_file` read this and stamp it onto the outbound
- * row so the host's a2a return-path routing can correlate replies back to
- * the originating session.
- *
- * This is module-level state on purpose: the agent-runner is single-process
- * and processes one batch at a time. Poll-loop calls `setCurrentInReplyTo`
- * before invoking the provider and `clearCurrentInReplyTo` after the batch
- * completes (or errors out).
- */
-let currentInReplyTo: string | null = null;
-
-export function setCurrentInReplyTo(id: string | null): void {
-  currentInReplyTo = id;
-}
-
-export function clearCurrentInReplyTo(): void {
-  currentInReplyTo = null;
-}
-
-export function getCurrentInReplyTo(): string | null {
-  return currentInReplyTo;
-}
-

container/agent-runner/src/db/session-state.ts

@@ -77,3 +77,47 @@ export function setContinuation(providerName: string, id: string): void {
 export function clearContinuation(providerName: string): void {
   deleteValue(continuationKey(providerName));
 }
+
+/**
+ * The a2a reply stamp: the id of the first inbound message in the batch the
+ * agent is currently processing. The poll loop publishes it at batch start;
+ * MCP tools (`send_message`, `send_file`) read it and stamp it onto outbound
+ * rows so the host's a2a return-path routing can correlate replies back to
+ * the originating session.
+ *
+ * This lives in outbound.db rather than module state because the MCP server
+ * runs as a separate stdio subprocess from the poll loop — module state set
+ * by the poll loop is invisible to it. Both processes open outbound.db
+ * (journal_mode=DELETE + busy_timeout make intra-container access safe).
+ */
+const IN_REPLY_TO_KEY = 'current_in_reply_to';
+
+/**
+ * Ignore a stamp older than this. The poll loop clears the stamp in a
+ * finally, but a container killed mid-batch (SIGKILL) can leave one behind;
+ * the guard stops a later out-of-batch read from picking up a dead stamp.
+ * Generous so a long-running batch's late sends still stamp correctly.
+ */
+const IN_REPLY_TO_MAX_AGE_MS = 30 * 60 * 1000;
+
+export function setCurrentInReplyTo(id: string | null): void {
+  if (id === null) {
+    clearCurrentInReplyTo();
+    return;
+  }
+  setValue(IN_REPLY_TO_KEY, id);
+}
+
+export function clearCurrentInReplyTo(): void {
+  deleteValue(IN_REPLY_TO_KEY);
+}
+
+export function getCurrentInReplyTo(): string | null {
+  const row = getOutboundDb()
+    .prepare('SELECT value, updated_at FROM session_state WHERE key = ?')
+    .get(IN_REPLY_TO_KEY) as { value: string; updated_at: string } | undefined;
+  if (!row) return null;
+  const age = Date.now() - new Date(row.updated_at).getTime();
+  if (!Number.isFinite(age) || age > IN_REPLY_TO_MAX_AGE_MS) return null;
+  return row.value;
+}

container/agent-runner/src/mcp-tools/core.test.ts

@@ -4,14 +4,31 @@
  * batch in poll-loop, and outbound writes from MCP tools (send_message,
  * send_file) must pick it up so a2a return-path routing on the host can
  * correlate replies back to the originating session.
+ *
+ * The stamp is published through session_state in outbound.db, not module
+ * state — the MCP server runs as a separate stdio subprocess from the poll
+ * loop, so it can only see the stamp through the shared DB. These tests seed
+ * it the same way the poll-loop process does (a direct DB write) rather than
+ * via any in-memory helper, so they exercise the real process boundary.
  */
 import { describe, it, expect, beforeEach, afterEach } from 'bun:test';
 
-import { initTestSessionDb, closeSessionDb, getInboundDb } from '../db/connection.js';
+import { initTestSessionDb, closeSessionDb, getInboundDb, getOutboundDb } from '../db/connection.js';
 import { getUndeliveredMessages } from '../db/messages-out.js';
-import { setCurrentInReplyTo, clearCurrentInReplyTo } from '../current-batch.js';
 import { sendMessage } from './core.js';
 
+/**
+ * Publish the a2a reply stamp the way the poll loop does: a direct write to
+ * session_state in outbound.db. `ageMs` back-dates updated_at to exercise the
+ * staleness guard MCP tools apply when reading it.
+ */
+function publishInReplyTo(id: string, ageMs = 0): void {
+  const updatedAt = new Date(Date.now() - ageMs).toISOString();
+  getOutboundDb()
+    .prepare('INSERT OR REPLACE INTO session_state (key, value, updated_at) VALUES (?, ?, ?)')
+    .run('current_in_reply_to', id, updatedAt);
+}
+
 beforeEach(() => {
   initTestSessionDb();
   // Seed a peer agent destination
@@ -24,13 +41,12 @@ beforeEach(() => {
 });
 
 afterEach(() => {
-  clearCurrentInReplyTo();
   closeSessionDb();
 });
 
 describe('send_message MCP tool — in_reply_to plumbing', () => {
-  it('stamps current batch in_reply_to on outbound rows', async () => {
-    setCurrentInReplyTo('inbound-msg-1');
+  it('stamps the batch in_reply_to (published via the DB) on outbound rows', async () => {
+    publishInReplyTo('inbound-msg-1');
 
     await sendMessage.handler({ to: 'peer', text: 'hello' });
 
@@ -40,7 +56,17 @@ describe('send_message MCP tool — in_reply_to plumbing', () => {
   });
 
   it('writes null when no batch is active', async () => {
-    // No setCurrentInReplyTo before this call — simulates ad-hoc / out-of-batch invocation.
+    // Nothing published to session_state — simulates ad-hoc / out-of-batch invocation.
+    await sendMessage.handler({ to: 'peer', text: 'hello' });
+
+    const out = getUndeliveredMessages();
+    expect(out).toHaveLength(1);
+    expect(out[0].in_reply_to).toBeNull();
+  });
+
+  it('ignores a stale stamp left behind by a killed container', async () => {
+    publishInReplyTo('inbound-msg-1', 60 * 60 * 1000); // an hour old
+
     await sendMessage.handler({ to: 'peer', text: 'hello' });
 
     const out = getUndeliveredMessages();

container/agent-runner/src/mcp-tools/core.ts

@@ -9,9 +9,9 @@
 import fs from 'fs';
 import path from 'path';
 
-import { getCurrentInReplyTo } from '../current-batch.js';
 import { findByName, getAllDestinations } from '../destinations.js';
 import { getMessageIdBySeq, getRoutingBySeq, writeMessageOut } from '../db/messages-out.js';
+import { getCurrentInReplyTo } from '../db/session-state.js';
 import { getSessionRouting } from '../db/session-routing.js';
 import { registerTools } from './server.js';
 import type { McpToolDefinition } from './types.js';

container/agent-runner/src/poll-loop.ts

@@ -2,8 +2,13 @@ import { findByName, getAllDestinations, type DestinationEntry } from './destina
 import { getPendingMessages, markProcessing, markCompleted, type MessageInRow } from './db/messages-in.js';
 import { writeMessageOut } from './db/messages-out.js';
 import { getInboundDb, touchHeartbeat, clearStaleProcessingAcks } from './db/connection.js';
-import { clearContinuation, migrateLegacyContinuation, setContinuation } from './db/session-state.js';
-import { clearCurrentInReplyTo, setCurrentInReplyTo } from './current-batch.js';
+import {
+  clearContinuation,
+  clearCurrentInReplyTo,
+  migrateLegacyContinuation,
+  setContinuation,
+  setCurrentInReplyTo,
+} from './db/session-state.js';
 import {
   formatMessages,
   extractRouting,