feat: add conversational replies and stable output

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a03397-4d51-7fd1-8ff2-946eb22ea2bc

SCOPE.md

@@ -17,8 +17,8 @@ tamq does not choose or infer them.
   acknowledgements, replay, export, and bounded purging.
 - Managed neutral-shell tmux lifecycle and explicit initial commands.
 - Durable manual send/inbox/acknowledgement with per-window repository identity,
-  shell-native address commands, comment-safe display, and explicit pull-time
-  filters.
+  shell-native direct and latest-counterparty reply commands, comment-safe
+  display, and explicit pull-time filters.
 - Sanitized one-time output notifications through target tmux pane PTYs, with
   inbox-only delivery as an explicit option and no foreground-process input.
 - Explicit opt-in control-mode pane delivery and the full-duplex `tamq tap` PTY
@@ -48,11 +48,11 @@ transport.
 
 | Intent capability | State | Evidence and remaining gap |
 | --- | --- | --- |
-| Direct repository addressing | Implemented for local alpha | Exact `gita` validation, per-session `@repo`/`@repo:` executable commands, and long-form parsing are covered without modifying shell configuration. |
+| Direct repository addressing | Implemented for local alpha | Exact `gita` validation, per-session `@repo`/`@repo:` commands, bare `@` latest-counterparty replies, and long-form parsing are covered without modifying shell configuration. |
 | Durable, inspectable local queue | Implemented | SQLite history, manual inbox, leases, endpoint records, inspect/history, JSONL export/replay, acknowledgement, and purge are present. |
 | Local socket service | Implemented | Peer-credential checks and structured ping/register/send/history/ack/endpoints/disconnect operations are tested. |
 | Neutral tmux session lifecycle | Implemented for local alpha | Repository-first startup opens untouched shells at exact gita paths, exports per-window identity, and runs no initial command unless `--command` is explicit. Stable reuse, service restart, and cleanup are covered by the installed-package test. |
-| Safe manual messaging | Implemented for local alpha | Normal endpoints write one sanitized comment to the target PTY output without injecting stdin; messages remain pending until acknowledgement. Inbox-only manual mode is explicit with `--no-display`, and legacy rows migrate to manual mode. |
+| Safe manual messaging | Implemented for local alpha | Normal endpoints write one sanitized comment above a stable shell input row without injecting stdin; conservative fallback handles the first row and alternate screens. Messages remain pending until acknowledgement. Inbox-only manual mode is explicit with `--no-display`. |
 | Full-duplex input observation | Explicit opt-in | `--tap --command ...` enables the PTY integration path. It is absent from neutral startup and remains covered for geometry, resize, raw mouse input, and lifecycle behavior. |
 | Bounded retry behavior | Not enforced | Failed output or injection remains pending and becomes claimable after lease expiry, but no attempt counter or terminal failure state applies the configured cap. |
 | Acknowledgement policy | Partially implemented | Terminal output remains pending until explicit acknowledgement, while legacy pane injection becomes `injected`; the configured `delivery_ack_mode` does not yet govern both paths. |
@@ -64,7 +64,8 @@ The terminal-neutral alpha path was exercised successfully on 2026-08-24 with
 an isolated installed tool. Repository-first startup created two ordinary
 shells at exact gita paths without sending initial keystrokes. The test proved
 per-window repository identity, stable reuse, shell-native addressing,
-comment-safe target output and inbox/filter/ack exchange, zero target-input
+latest-counterparty replies, comment-safe target output above an unchanged
+partial input line and cursor, inbox/filter/ack exchange, zero target-input
 mutation, service restart, endpoint disappearance, explicit initial-command
 startup, and cleanup.
 
@@ -86,7 +87,7 @@ Not yet suitable:
   and stronger process-supervision evidence.
 - Cross-host messaging or use as a general-purpose broker.
 
-The suite currently has 93 passing tests and 76% statement coverage. Coverage
+The suite currently has 100 passing tests and 76% statement coverage. Coverage
 is strongest in durable storage and registry handling, and weakest in the PTY
 tap and CLI orchestration; PTY statement coverage increased from 23% to 33%,
 while subprocess behavior is primarily proven by the real-tmux test. The