feat: pi agent watcher

[mbcrocci]

Adds a new watcher for the pi coding agent.
It reads sessions jsonl transcripts to detect the harness' status.

[Palanikannan1437]

Thanks for the effort @mbcrocci, overall the structure closely follows our existing JSONL watchers and the code is clean.

I verified against the real Pi data on my machine and caught a few issues, most notably a status flicker bug and a missing seed emit that the other watchers all have now.

Main things to fix:

1. toolResult role causes idle flicker mid-turn — confirmed with real Pi JSONL data
2. Missing seed-time emit — Pi agents running at startup won't show in the TUI
3. decodeProjectDir breaks on hyphenated paths — confirmed with real path /Users/.../mi-pi

See inline comments for details 👇

[Palanikannan1437]

This is the biggest gap vs. the other watchers right now! All of them (codex, claude-code, amp, opencode) emit non-idle sessions after the seed scan completes — that's what populates the TUI sidebar when the server starts up.

Your scan() sets this.seeded = true but never loops through this.sessions to emit them. Compare with the Codex watcher's finally block:

if (!this.seeded) {
  this.seeded = true;
  for (const [threadId, snapshot] of this.sessions) {
    if (snapshot.status === "idle" || !snapshot.projectDir) continue;
    const session = this.ctx?.resolveSession(snapshot.projectDir);
    if (!session) continue;
    this.ctx?.emit({
      agent: "pi",
      session,
      status: snapshot.status,
      ts: Date.now(),
      threadId: snapshot.sessionId ?? threadId,
      ...(snapshot.threadName && { threadName: snapshot.threadName }),
    });
  }
}

Without this, if Pi is mid-task when the server starts, it'll be invisible in the sidebar until the next status change.

[mbcrocci]

I've added the codex block almost exactly, but I'm not sure if the issue is fixed.

In my setup, no sessions show up until I initiate the conversion (even if resuming a session). But this happens in Pi, OpenCode and Codex.

[Palanikannan1437]

no no i meant if the tui was quit and restarted, if say you were running 4 sessions and then quit the sidebar (using q) or updated the version (using tpm update flow), it would seed your data back in for the running sessions on restart, I'll check it though once

[mbcrocci]

Hi, thank you for your thorough review and the project - it's really cool!
I've addressed all the issues and in my testing it provided a much better experience, specially the flickering bug.

There are two pending issues I detected that I'm not sure if they are related to the pi-watcher or my specific tmux setup:
1 - Agent sessions don't appear in the sidebar until I talk in them with pi as well as opencode and codex (I commented this in the related PR comment)
2 - Sometimes (cannot reliably reproduce) agent sessions from my second sessions only appear in my first tmux session

Let me know if there is anything else that needs fixing.

[rs545837]

/inspect

[inspect-review]

inspect review

Triage: 37 entities analyzed | 0 critical, 0 high, 3 medium, 34 low
Verdict: standard_review

Findings (3)

1. [low] Seed scan can crash after stop(): scan()'s finally block uses this.ctx.resolveSession(...) and this.ctx.emit(...) without re-checking this.ctx. stop() sets this.ctx = null, so if stop() is called while scan() is in-flight, finally will throw. Evidence: stop(): this.ctx = null; and scan() finally: const session = this.ctx.resolveSession(snapshot.projectDir); ... this.ctx.emit({ ... }).
2. [low] Incremental tail parsing can permanently drop entries when the last JSONL line is partially written: processFile() advances snapshot.fileSize to fileStat.size even if applyEntries() skips a truncated JSON line (JSON.parse fails). On the next run, those bytes are no longer re-read, so the entry is lost. Evidence: incremental path sets nextSnapshot = applyEntries(text, { ...prev, fileSize: fileStat.size }); and applyEntries(): try { entry = JSON.parse(rawLine); } catch { continue; } with no buffering/retry of the incomplete last line.
3. [low] sessions Map key collision across directories: sessions are keyed only by threadId parsed from filename, ignoring the encoded directory. Two different projects with the same session-id suffix will overwrite each other, mixing state and emitting against the wrong session. Evidence: const threadId = parseThreadId(filePath); const prev = this.sessions.get(threadId); ... this.sessions.set(threadId, nextSnapshot); and parseThreadId uses only basename split on '_' (return name.split('_').at(-1) ?? name;).

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Reviewed by inspect | Entity-level triage found 0 high-risk changes

[Palanikannan1437]

hey @mbcrocci, merged! thanks for the clean work and for sticking with the review — appreciate it. those two issues you mentioned aren't related to the pi watcher, will look into them separately. welcome to the project 🙌