feat(create/monitor): implement automatic UUID materialization, auto-pinning, and drift-C2 resolution (13/13 PASS)

.agents/skills/multi-agent-mux-create/SKILL.md

@@ -233,10 +233,10 @@ The script handles the YAML append, pane capture, and the `last_visible_status`
 ## Pitfalls
 
 - **Don't use `nohup`/`disown`/`setsid` for the agent itself** — those background the agent outside herdr. The whole point of this skill is *the herdr session is the supervisor*. `nohup` is OK only for *launching the wrapper* (which itself creates the herdr session via `herdr new-session -d`).
-- **Don't trust `--session-id <uuid>` flags blindly** — claude/agy may not accept a fixed session id on first spawn. The session id is *assigned* on first user message; you can read it back from `~/.claude/projects/.../session.jsonl` headers or `~/.gemini/.../cache/last_conversations.json` AFTER the first message.
+- **Claude Session ID Auto-Assignment**: Fresh `claude` sessions automatically generate a new UUID (`mam_gen_uuid`) passed via `claude --session-id <uuid>`. `claude_session_id_own` is stored in `.mam/agent-sessions.yaml` with `session_id_source: assigned` and `session_id_verified: false`.
+- **First Message Materialization**: The transcript file `.jsonl` is created on disk when the first user prompt is sent. The monitor loop (`reconcile.sh`) verifies the transcript and promotes `session_id_verified: true` and `last_visible_status: pinned`.
 - **Wrapper script MUST NOT be created via `hermes profile alias`** — that command writes a `hermes -p <profile>` wrapper that destroys the herdr behavior. Create wrappers manually (see `lab-landing-page-creator-claude` template).
 - **Always use the workspace-relative path** in herdr `cwd` — relative paths break when herdr respawns in a different shell context.
-- **The first `claude` message generates the session id** — `multi-agent-mux-create` only sets up the *container*. If you need a known session id for later resume, send a placeholder message (e.g. "init") and read it back, then call `multi-agent-mux-resume` later.
 
 ## Verification
 

.agents/skills/multi-agent-mux-create/scripts/create_session.sh

@@ -148,8 +148,13 @@ if [ "$(uname)" = "Darwin" ] && [ -f "$RESOLVED_BIN" ]; then
   xattr -d com.apple.quarantine "$RESOLVED_BIN" 2>/dev/null || true
 fi
 
+SESSION_UUID=""
+if [ "$AGENT" = "claude" ]; then
+  SESSION_UUID="$(mam_gen_uuid)"
+fi
+
 case "$AGENT" in
-  claude) CMD_FULL="${RESOLVED_BIN} --dangerously-skip-permissions" ;;
+  claude) CMD_FULL="${RESOLVED_BIN} --dangerously-skip-permissions --session-id ${SESSION_UUID}" ;;
   agy)    CMD_FULL="${RESOLVED_BIN} --dangerously-skip-permissions" ;;
   hermes) CMD_FULL="${RESOLVED_BIN}" ;;
   cline)  CMD_FULL="${RESOLVED_BIN} -i" ;;
@@ -162,6 +167,7 @@ spawn() {
   case "$AGENT" in
     claude)
       if { [ -x "$WRAPPER" ] && [ "$(basename "$WRAPPER")" != "claude" ]; } || [ "$USE_WRAPPER" = "1" ]; then
+        SESSION_UUID=""
         nohup "$WRAPPER" >/dev/null 2>&1 &
         disown
       else
@@ -262,6 +268,7 @@ atomic_dump_yaml "$AGENT_SESSIONS_YAML" \
   HERDR_EPOCH="$HERDR_EPOCH" PANE_PID="$PANE_PID" PANE_CWD="$PANE_CWD" \
   CMD_FULL="$CMD_FULL" START_CMD="$START_CMD" CHILD_PID="$CHILD_PID" \
   HERDR_SESSION_NAME="${HERDR_SESSION_NAME:-default}" \
+  SESSION_UUID="$SESSION_UUID" \
   DELEGATE_JOB_ID="$DELEGATE_JOB_ID" ROLE="$ROLE" <<'PYEOF'
 name = os.environ['SESSION_NAME']
 agent = os.environ['AGENT']
@@ -302,8 +309,6 @@ entry = {
     'kill_command': f'HERDR_SESSION_NAME={server_name} herdr kill-session -t {name}',
 }
 
-
-
 if agent == 'claude':
     entry['tui'] = {
         'model': '(unknown — capture after first message)',
@@ -312,8 +317,11 @@ if agent == 'claude':
         'account': '(unknown — read from claude auth status)',
         'version': '(unknown — read from TUI)',
     }
-    entry['claude_session_id_own'] = None
-    entry['last_visible_status'] = "unverified"
+    assigned = os.environ.get('SESSION_UUID', '') or None
+    entry['claude_session_id_own'] = assigned
+    entry['session_id_source'] = 'assigned' if assigned else 'pending-discovery'
+    entry['session_id_verified'] = False
+    entry['last_visible_status'] = "assigned (awaiting first message)" if assigned else "unverified"
 elif agent == 'agy':
     cp = os.environ.get('CHILD_PID', '0')
     entry['child_pid'] = int(cp) if cp.isdigit() else 0