fix(channel): remove "Received. Working..." ack-placeholder + AX-SIGNALS-001 spec

[madtank]

Summary

• Removes the ensureAckMessage() ack-placeholder pattern from channel/server.ts that was causing stuck Received. Working... rows in the channel
• Brings the deployed channel runtime into the repo as the canonical source (the deployed version had drifted ~163 lines from the in-repo source)
• Adds specs/AX-SIGNALS-001/spec.md — full design intent for agent status signals (signals vs noise standard, 6-criterion gate, 5-phase migration path, thought bubble pattern for outbound rich-presence and inbound spinner pill for "did my message land" confirmation)
• Adds @anvil to .github/CODEOWNERS as co-owner of the repo, channel/, and specs/

Why the diff is large

Most of the 269 lines added are not the fix — they're the deployed-to-repo sync of channel/server.ts. The deployed runtime at /home/ax-agent/channel/server.ts had been edited live to add multi-parent ack state (Map<string, PendingReplyState>) and the broken ensureAckMessage() function. None of those changes were ever committed back to the repo, so the in-repo version was missing them entirely. This commit brings the deployed state into the repo as the new baseline, then removes the only ensureAckMessage() call site as part of the same change. The function definition stays as dead code for now — a follow-up commit can clean up the orphaned helpers without coupling that cleanup to the user-visible fix.

What the actual fix is

A 5-line removal in the SSE handler at channel/server.ts:654-658:

   if (mentionQueue.length > QUEUE_MAX) mentionQueue.shift();

-  try {
-    await ensureAckMessage(mention.id);
-  } catch (err) {
-    log(`ack send failed for ${mention.id.slice(0, 12)}: ${err}`);
-  }
-
   // Deliver to Claude Code session

After this, the reply tool falls through to its existing sendMessage() else-branch — same behavior the channel had before the placeholder pattern was added.

Test plan

• bun build server.ts --target=node — bundles 217 modules cleanly
• Symbol audit: ensureAckMessage has zero call sites; the only pendingReplies.set() is inside the orphaned function itself
• End-to-end after Claude Code session restart: @anvil mentions land as a single substantive reply, no preceding Received. Working... placeholder
• Verify on a fresh machine after pulling this branch + restarting the channel MCP

What's NOT in this PR (intentional)

• The dead-code cleanup of ensureAckMessage(), startHeartbeat(), stopHeartbeat(), clearPendingReply() definitions — leaves a smaller follow-up
• AX-SIGNALS-001 Phases 2-5 (sentinel prompt fix, backend SSE filter, in-place inbound pill, outbound thought bubble, formal agent_status message_type) — design only, implementation comes later
• The AX-SCHEDULE-001 spec sitting untracked in the working tree — not authored by me, leaving for the original author to commit
• A separate fix for the messages_notifications.broadcast_sse() early-return that should call is_ui_only_no_reply_metadata() (real backend bug, but separable from this CLI-side fix)

Related

• Spec: specs/AX-SIGNALS-001/spec.md (added by this PR)
• Memory entry: `agent-side memory file pointing at the spec (so future-anvil sessions don't redo this design)
• Context entry on aX platform: .ax/signals-design-intent (the wiki entry the concierge can read)

🤖 Generated with Claude Code