feat: add shell-native message routing

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

README.md

@@ -57,7 +57,24 @@ windows and never run another initial command in them.
 ## Exchange messages manually
 
 Each managed shell exports its own repository slug as `TAMQ_REPO`. From the
-`flex-auth` window, queue a message:
+`flex-auth` window, queue a message using the repository command installed for
+the session:
+
+```bash
+@audit-core: please review the auth boundary
+```
+
+The spelling without the trailing colon is equivalent:
+
+```bash
+@audit-core please review the auth boundary
+```
+
+These are tamq-owned executable commands beside the installed `tamq` command,
+not shell-specific aliases. Set `TAMQ_COMMAND_DIR` before startup to select a
+different writable command directory already present on your shell's `PATH`.
+Tamq refuses to overwrite unrelated commands. The shims only use tamq's durable
+send operation. The long form remains available:
 
 ```bash
 tamq send '@audit-core: please review the auth boundary'
@@ -70,14 +87,33 @@ tamq inbox
 tamq ack <message-id>
 ```
 
+Human inbox output is safe to paste into an ordinary shell because every line
+is a comment. It includes the durable id needed by `ack`:
+
+```text
+#flex-auth: please review the auth boundary [m-...]
+```
+
+To explicitly consume pending messages through a command, use an inbox filter:
+
+```bash
+tamq inbox --filter 'cat >> msg.log'
+```
+
+The command runs once per pending message with the comment form on standard
+input. `TAMQ_MESSAGE_ID`, `TAMQ_SENDER_REPO`, and `TAMQ_TARGET_REPO` are set in
+its environment. A zero exit acknowledges that message; a non-zero exit leaves
+it and all later messages pending. Filters never run in the background and
+cannot be combined with `--all` or `--json`.
+
 Outside a managed window, use `tamq inbox --repo audit-core` and optionally
 `--json`. Manual messages remain durable and pending until acknowledged. They
 are never injected as terminal keystrokes, so they cannot corrupt a command
 being typed in the target pane.
 
-After upgrading from the earlier Codex-default alpha, recreate the managed
-session once so existing panes are replaced by neutral shells and the broker is
-re-registered in manual delivery mode:
+After upgrading from an earlier alpha, recreate the managed session once so
+existing panes inherit the neutral shell contract, repository command `PATH`,
+and manual broker registration:
 
 ```bash
 tamq stop