Track live commands with /track (initial slice of #393)

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Goal

Initial implementation of #393 built on NMSh's existing finite-command /watch scheduler. This is a post-v0.20 draft and must not merge into the ongoing v0.20 release candidate.

Implemented

• /track df -h /Volumes/T7Projects and /track --every 5s -- docker system df; native alias sharing the scheduler and manager with /watch.
• List, pause, resume, refresh, stop, multiple finite trackers. One current and previous snapshot, no repeated foreground transcript entries.
• Exact read-only Docker disk-report allowance; unknown Docker commands still require confirmation.
• Snapshot freshness, current exit code, and explicit C-to-copy the latest sanitized display snapshot.
• Display-control sanitization, child stdio close before snapshot, and no overlapping manual refreshes.
• Regression tests and docs/development/track-live-command-refresh.md.

Still outstanding in #393

• Service-owned detach/reattach tracking via Background tasks: supervised long-running commands, task bar above the composer, and conservative suggestions #382; the existing engine is window-scoped.
• True persistent transcript block and raw-byte copy/search semantics; current UI is live strip + detail panel.
• Physical Ghostty/Terminal.app/Linux/Fish QA and full performance/lifecycle acceptance.
• Further timeout/termination and repeated side-effect hardening.

Release coordination

Based on release/v0.20.0 for interface compatibility, not in v0.20 scope. Do not merge until separately approved. Frozen #359 branches, Opus release heads, site, tap and history are untouched. PR CI is new and must be checked; no claims of completed physical verification.

Refs #393, #382, #388.

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/track hardening review — exact-head verification

Review/fix head: d72aeb8aeb86e3a27923d0db5b3d562a45bb9709.

Published PR CI 38715312969 completed successfully on attempt 1 at this head: both macOS and Ubuntu shards, Node 22 compatibility, Quality and aggregate Verify (22.x/26.x) all passed. PR-triggered Fedora and both timing smoke jobs are skipped by workflow design; they are not acceptance evidence here. Physical terminal/clipboard QA remains unperformed.

Problems found and corrected: the first PR CI (38710353898) exposed missing Ask coverage and altered palette ranking; both were corrected without changing palette order. An intermediate macOS shard exposed two test-portability assumptions (OS-specific spawn error code and a width-clipped fallback message); assertions now check failure semantics and safety at the actual visible width. Earlier failed/cancelled runs remain recorded, not reclassified as flakes.

Hardened behaviors:

• Strict finite cadence parsing (no invalid/overflow timer fallback), 2s/15s minima, 60m upper bound, eight active trackers, bounded retention.
• No overlapping refreshes; manual requests report whether a run actually began.
• Byte-bounded (200 KB) incremental UTF-8 capture and truthful truncation, error, signal and timeout presentation; waits for stdio close before freezing a snapshot.
• Owned process-group SIGTERM then bounded SIGKILL escalation; closes inherited output pipes on timeout/forced stop. No claim of controlling descendants that escape the owned group.
• Repeated shell substitutions, heredocs and detached background operators refused; unknown side effects remain opt-in; exact read-only docker system df is allowed.
• Direct-copy of latest sanitized snapshot (not previous samples), with explicit clipboard failure messaging and no hidden review bypass in narrow terminals.
• Focused regression tests for parsing/safety, freshness/copy, output limits, concurrent trackers, unavailable commands/cwd, and narrow confirmation fallback.

Scope limits: This is an initial window-scoped /watch-based feature, not the service-owned persistent inline transcript-block implementation from #393. Detach/reattach continuity, physical QA, independent non-PR timing/Fedora coverage and full #393 acceptance remain pending. Keep the PR draft and out of the v0.20 release candidate; no automatic release merge.

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Its base release/v0.20.0 is now released as v0.20.0 (#392). /track (#393) stays future work; retarget this draft to master before review.

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v0.21 handoff (2026-10-18): Retargeted this draft from the released/stale release/v0.20.0 base to current dev (now fast-forwarded to match master). Treat d72aeb8a as an implementation reference, not a merge-ready acceptance. Before reuse, rebase/integrate on the exact v0.21 branch, inspect conflicts and regressions with the now-shipped #382 background supervisor, and deliver #393's session-owned lifecycle, live-block/transcript semantics, raw-vs-sanitized copy/search, safe repetitive execution, and physical QA. Preserve existing /watch, PTY/input ownership and confirmed release behavior. Leave this PR draft until implementation is re-reviewed; do not blindly squash it into dev.

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v0.21 reconciliation: this draft's WatchTasks.ts and WatchPanel.ts were carried as written into #416 (neither file changed on dev since this branch's base), together with tests/track.test.ts; its app and slash edits were re-applied by hand on current dev. #416 adds the in-place transcript block, live-PATH samples, /track copy and the final result on stop. This draft was not merged and can be closed once #416 lands.

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Closing as superseded by #416 (merged into dev as a5f2fd69, part of the v0.21 line). Nothing here is lost:

• src/tasks/WatchTasks.ts and src/tasks/WatchPanel.ts were taken from this PR as written (neither had changed on dev since this PR's base). They were then hardened in fix(v0.21): harden /track refresh and finalization lifecycle #420 and /track review: repetition safety gate, process cleanup, bounded presentation #421: refresh and finalization lifecycle, the repetition safety gate, and process-group cleanup.
• All 8 tests in tests/track.test.ts are kept on dev. The alias test is now /track shares the /watch scheduler and parser; it is flagged for its transcript block.
• The app and slash-command edits were re-applied by hand on the current base. docs/development/track-live-command-refresh.md was revised to match what ships.

Verified in the v0.21.0 release audit against dev 433af8fd. The branch feature/track-live-command-refresh is left in place for reference.