fix(pi): align the doctor with the pi resolver, correct the strip rationale, update the skill

Second review pass on #282, the three items left open after f4dcfbe.

1. `codeman doctor` and the run mode disagreed about pi. The registry entry
   accepted a bare `which pi` hit while pi-cli-resolver demanded semver-shaped
   `--version` output, so the Dependencies panel could report an installed Pi CLI
   on a box where Run Pi stays hidden, which reads as a broken mode rather than a
   missing install. Both sides now share one exported PI_VERSION_REGEX, and
   PathResolver gains an opt-in `requireVersionMatch` so a binary that fails the
   shape check is reported MISSING instead of installed-with-unknown-version.
   Only pi sets it; every other tool keeps its current behaviour.

2. The isAltScreenStripMode comment justified excluding pi with "the alt screen
   is load-bearing for its fullscreen TUI". That is not what exclusion does: pi
   is tmux-backed, so it falls through to isMuxAltScreenOnlyStripMode, which
   strips the alt-screen toggles anyway. What exclusion actually preserves is
   `\x1b[3J` and the mouse DECSETs, which is the real reason (pi renders into the
   main screen and is mouse-aware). Comment and changeset now say that, and state
   the consequence: fullscreen pi paints into the main buffer, like vim in a tmux
   shell session.

3. skills/codeman still enumerated the five pre-pi modes in nine places, telling
   agents a backend does not exist and understating class-wide caveats by one
   mode. All updated, plus stale session.ts line references refreshed.

Tests: a new static guard derives the mode set from the Zod schema (not a copy)
and fails when a skill enumeration lists a partial set of external CLIs, verified
by mutation. It also documents the one legitimate exception it found: the "writes
no transcript" lists drop codex, which does write a rollout Codeman reads back.
Plus doctor cases for an unrelated `pi` on PATH and registry/resolver regex parity.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

skills/codeman/SKILL.md

@@ -568,7 +568,7 @@ recovered by submitting it with `{"input":"\r"}`.
 
 ⚠️ `stop` and `blocked` fire for `claude` sessions only (they are Claude Code hooks,
 and only when the workspace actually has them, see [§5.1](#51-where-to-spawn)). On
-`shell`/`opencode`/`codex`/`gemini`/`antigravity`, requesting them explicitly is a
+`shell`/`opencode`/`codex`/`gemini`/`antigravity`/`pi`, requesting them explicitly is a
 400, and lifecycle transitions there are coarse (a short shell command may emit **no**
 `idle` transition at all, verified live), so synchronize those with markers.
 
@@ -594,7 +594,8 @@ from the transcript file, which is flushed slightly *after* the `stop` hook fire
 single read taken the instant send-and-wait returns comes back `""` even though the
 turn finished (verified live: empty on the first call, full text seconds later). `text`
 is also `""` before the worker's first completed turn, and always `""` for modes with
-no transcript (`shell`, `opencode`, `gemini`, `antigravity`, verified live), which is
+no transcript (`shell`, `opencode`, `gemini`, `antigravity`, `pi`; the first four
+verified live, pi from the same source path), which is
 why the loop above is bounded rather than open-ended. Fall back to the terminal buffer
 there, tail in **bytes** (`textOutput` in `GET .../output` stays empty for interactive
 sessions; don't use it):
@@ -678,7 +679,7 @@ turn), and both better than diffing terminal samples:
 ```
 
 ⚠️ `active-tools` is parsed out of Claude's own output format, so it is **empty for
-`opencode`/`codex`/`gemini`/`antigravity`** (those parsers are skipped wholesale) and
+`opencode`/`codex`/`gemini`/`antigravity`/`pi`** (those parsers are skipped wholesale) and
 in practice empty for `shell`. Source-verified, not measured live.
 
 Only if neither helps: sample `terminal?tail=` twice a few seconds apart. A changing

skills/codeman/reference/endpoints.md

@@ -237,7 +237,7 @@ minutes, never retry the credential.
 flushed slightly *after* the `stop` hook fires, so a read taken the instant the wait
 returns is too early (verified live: empty on the first call, full prose seconds later).
 It is also `""` before the worker's first completed turn, and permanently `""` for
-`shell`, `opencode`, `gemini` and `antigravity`, which write no transcript.
+`shell`, `opencode`, `gemini`, `antigravity` and `pi`, which write no Claude transcript.
 
 **Fix** Poll it, bounded (10 tries, 1 s apart). If it is still empty on a hook-less mode,
 that is expected, not a failure: read `terminal?tail=` and strip ANSI instead.
@@ -334,7 +334,7 @@ ESC=$(printf '\033')
 
 `POST /api/v1/quick-start` body (all optional):
 `{"caseName":"worker-1","mode":"claude","sessionName":"w9-worker","effort":"high"}`
-,  `mode` ∈ `claude|shell|opencode|codex|gemini|antigravity`; response is
+,  `mode` ∈ `claude|shell|opencode|codex|gemini|antigravity|pi`; response is
 `.data.{sessionId, caseName, casePath}`. Creates the case directory (a real directory
 on the user's disk) if missing, do not retry it in a loop, and remember the name.
 
@@ -450,9 +450,9 @@ Quirks that will bite you:
   session answers with an empty timeline rather than a 404.
 - ⚠️ **`active-tools` proves presence, never absence.** It is fed by the BashToolParser,
   which reads Claude's rendered `● Bash(…)` lines, and `_processExpensiveParsers`
-  returns early for every external CLI mode (`session.ts:2086`), so it is permanently
-  `[]` on `opencode`/`codex`/`gemini`/`antigravity`. ⚠️ **`shell` is NOT one of those**
-  (`isExternalCliMode`, `session.ts:164-166`, lists only those four), so the parser does
+  returns early for every external CLI mode (`session.ts:2136`), so it is permanently
+  `[]` on `opencode`/`codex`/`gemini`/`antigravity`/`pi`. ⚠️ **`shell` is NOT one of those**
+  (`isExternalCliMode`, `session.ts:165-167`, lists only those five), so the parser does
   run on a shell worker, and `TEXT_COMMAND_PATTERN` (`bash-tool-parser.ts:88`) matches
   bare `tail|cat|head|less|grep|watch|multitail <path>` lines with no `● Bash(` wrapper:
   a shell worker running `cat build.log` really does populate this. In practice it stays

skills/codeman/reference/messaging.md

@@ -56,7 +56,7 @@ own head: the worker enforcing the cap is the one who has to be told about it.
 | synchronize on end of turn | HTTP `wait until=stop` (fires for message-initiated turns too, verified live) |
 | liveness / death check | HTTP `wait?until=exit` |
 | interrupt a running turn (break-glass) | HTTP input, a bare `\x1b` with no `\r` |
-| non-claude modes (`shell`/`opencode`/`codex`/`gemini`/`antigravity`) | HTTP only (no other CLI has messaging) |
+| non-claude modes (`shell`/`opencode`/`codex`/`gemini`/`antigravity`/`pi`) | HTTP only (no other CLI has messaging) |
 | delete | HTTP, via SKILL.md's `delete_session` guard |
 
 ## Availability: probe, never assume
@@ -345,7 +345,7 @@ Without a break-glass, a pair with a bad brief is a token bonfire with no off sw
 
 ### Mixed fleets: the pairing matrix
 
-Non-claude workers (`shell`, `opencode`, `codex`, `gemini`, `antigravity`) cannot be peers
+Non-claude workers (`shell`, `opencode`, `codex`, `gemini`, `antigravity`, `pi`) cannot be peers
 at all; no other CLI has this feature. Their tasks route over HTTP, and you never mention
 messaging in their briefs. The claude half of the fleet can use messaging among itself,
 subject to the namespace rule: **messaging works between two sessions that share one

skills/codeman/reference/recipes.md

@@ -177,7 +177,7 @@ for _ in $(seq 1 10); do
 done
 printf '%s\n' "$TXT"
 #    (.data is {text,timestamp}; text is also "" before the first completed turn and
-#     always "" for shell/opencode/gemini/antigravity, which have no transcript, use
+#     always "" for shell/opencode/gemini/antigravity/pi, which have no transcript, use
 #     the terminal tail there, and here only to diagnose an unsubmitted prompt.)
 
 # 6. clean up: exact id, own list only, through the fail-closed preamble helper