Document plugins update JSON stderr-only not-found

Constraint: ROADMAP-only dogfood follow-up for 23:00 nudge on rebuilt claw git_sha 5eb1d7d

Rejected: implementation change to plugin lifecycle update; request was one concrete follow-up if no backlog item
Confidence: high after repeated bounded samples plus prompt list sanity check
Scope-risk: narrow
Directive: Replaces invalid hang PR ultraworkers#2894 with verified stderr-only JSON-mode gap
Tested: cargo run --manifest-path rust/Cargo.toml --bin claw -- version --output-format json; repeated timeout 8 ./rust/target/debug/claw plugins update does-not-exist --output-format json; timeout 8 ./rust/target/debug/claw plugins list --output-format json; git diff --check; scripts/fmt.sh --check
Not-tested: runtime behavior change, because this commit only documents the gap

Author: Yeachan-Heo

ROADMAP.md

@@ -6291,3 +6291,4 @@ Original filing (2026-04-18): the session emitted `SessionStart hook (completed)
 349. **Top-level `plugins show <name> --output-format json` returns success-shaped JSON for an unsupported plugin action instead of a typed unsupported-action error** — dogfooded 2026-04-29 for the 21:30 nudge on current `origin/main` / rebuilt `./rust/target/debug/claw` with embedded `git_sha` `a2a38df9`. After rebuilding and verifying the binary provenance, repeated bounded runs of `./rust/target/debug/claw plugins show does-not-exist --output-format json` returned stdout JSON with `{"action":"show","kind":"plugin","message":"Unknown /plugins action 'show'. Use list, install, enable, disable, uninstall, or update.","reload_runtime":false,"target":"does-not-exist"}` and no stderr. The command therefore reports the requested unsupported action as the top-level `action:"show"` and exits successfully while hiding the failure class inside a human `message`; it does not provide `status:"unsupported_action"`, `code:"plugin_action_unsupported"`, or structured `supported_actions[]`. This is distinct from #348's prose-only plugin inventory schema: #348 covers `plugins list` payload shape, while this pinpoint covers unsupported plugin action classification and recovery metadata. **Required fix shape:** (a) return a typed stdout JSON error or explicit non-ok status for unsupported plugin actions, with `requested_action`, `supported_actions`, and `target` fields; (b) do not label the primary `action` as the unsupported requested verb unless a separate `status`/`code` makes the failure unambiguous; (c) keep the human message optional and avoid making it the only way to detect the unsupported action; (d) add regression coverage proving `plugins show foo --output-format json` is machine-classifiable as unsupported without scraping prose. **Why this matters:** plugin lifecycle automation follows action/status fields. If an unsupported mutation/inspection verb returns success-shaped JSON and only says "Unknown" in prose, claws can treat a failed preflight as a valid plugin show result and continue toward unsafe lifecycle actions. Source: gaebal-gajae dogfood follow-up for the 21:30 nudge on rebuilt `./rust/target/debug/claw` `a2a38df9`; invalid hang PR #2885 was closed after repeated bounded repros returned stdout JSON.
 350. **Top-level `plugins enable <missing-plugin> --output-format json` hangs with zero stdout/stderr instead of returning a typed plugin-not-found or unsupported-target response** — dogfooded 2026-04-29 for the 22:00 nudge on current `origin/main` / rebuilt `./rust/target/debug/claw` with embedded `git_sha` `ee44ff98`. After rebuilding and verifying the binary provenance, repeated bounded runs of `timeout 8 ./rust/target/debug/claw plugins enable does-not-exist --output-format json` exited `124` with `stdout=0` and `stderr=0`; a third sample was still stuck until killed. In the same rebuilt binary, `plugins list --output-format json` returned promptly with the known plugin inventory payload, proving the plugin top-level surface is reachable and narrowing the hang to missing-plugin lifecycle mutation. This is distinct from #348's prose-only list inventory and #349's unsupported `plugins show` success-shaped JSON: #350 covers a supported lifecycle verb (`enable`) against an absent target, where the CLI should be able to fail fast before any plugin runtime work. **Required fix shape:** (a) validate the target plugin against the discovered/configured inventory before invoking enable-side effects; (b) return bounded stdout JSON such as `kind:"plugin"`, `action:"enable"`, `status:"not_found"` or `kind:"error"`, `code:"plugin_not_found"`, `plugin`, and optional `available_plugins[]`; (c) add internal timeout/diagnostic metadata for plugin lifecycle operations so registry or hook stalls do not produce silent zero-byte hangs; (d) add regression coverage proving `plugins enable does-not-exist --output-format json` returns a typed JSON outcome within a deterministic budget and does not mutate plugin state. **Why this matters:** enable/disable/update/uninstall are destructive control-plane actions. A missing or stale plugin name must fail safely and machine-readably; otherwise claws cannot preflight plugin lifecycle operations, distinguish typo from loader deadlock, or recover without killing a hung process. Source: gaebal-gajae dogfood follow-up for the 22:00 nudge on rebuilt `./rust/target/debug/claw` `ee44ff98`.
 351. **Top-level `plugins disable <missing-plugin> --output-format json` sends the JSON error envelope to stderr only, leaving stdout empty** — dogfooded 2026-04-29 for the 22:30 nudge on current `origin/main` / rebuilt `./rust/target/debug/claw` with embedded `git_sha` `0f9e8915`. After rebuilding and verifying the binary provenance, repeated bounded runs of `timeout 8 ./rust/target/debug/claw plugins disable does-not-exist --output-format json` exited `1` with `stdout=0` and `stderr=113`; stderr contained JSON (`{"error":"plugin `does-not-exist` is not installed or discoverable","hint":null,"kind":"unknown","type":"error"}`), but stdout was empty. In the same rebuilt binary, `plugins list --output-format json` returned stdout JSON promptly with the known plugin inventory payload, proving the plugin command surface is reachable. This is distinct from #350's missing-target `plugins enable` zero-byte timeout: the disable path fails fast, but its JSON-mode error envelope is routed to stderr and uses generic `kind:"unknown"`/`type:"error"` instead of a plugin-specific stdout outcome. **Required fix shape:** (a) define and consistently document whether JSON mode emits machine-readable envelopes on stdout, stderr, or both for nonzero exits; (b) return a plugin-specific typed error with `kind:"plugin"` or `domain:"plugin"`, `action:"disable"`, `status:"not_found"` or `code:"plugin_not_found"`, `plugin`, and optional `available_plugins[]`; (c) keep stdout/stderr placement consistent across plugin lifecycle verbs so callers do not need per-action stream heuristics; (d) add regression coverage proving `plugins disable does-not-exist --output-format json` produces a typed plugin-not-found JSON contract on the documented stream. **Why this matters:** disable is a recovery/control-plane operation. A stale plugin name should be a structured, domain-specific not-found result on a predictable stream; otherwise claws that read stdout JSON for normal responses and stderr for human diagnostics must special-case this lifecycle failure. Source: gaebal-gajae dogfood follow-up for the 22:30 nudge on rebuilt `./rust/target/debug/claw` `0f9e8915`; invalid hang PR #2891 was closed after repeated bounded repros returned exit 1 with JSON on stderr.
+352. **Top-level `plugins update <missing-plugin> --output-format json` sends a generic JSON error envelope to stderr only, leaving stdout empty** — dogfooded 2026-04-29 for the 23:00 nudge on current `origin/main` / rebuilt `./rust/target/debug/claw` with embedded `git_sha` `5eb1d7d8`. After rebuilding and verifying the binary provenance, repeated bounded runs of `timeout 8 ./rust/target/debug/claw plugins update does-not-exist --output-format json` exited `1` with `stdout=0` and `stderr=97`; stderr contained JSON (`{"error":"plugin `does-not-exist` is not installed","hint":null,"kind":"unknown","type":"error"}`), but stdout was empty. In the same rebuilt binary, `plugins list --output-format json` returned stdout JSON promptly with the known plugin inventory payload. This is distinct from #350's missing-target `plugins enable` zero-byte timeout and parallel to #351's `plugins disable` stderr-only JSON envelope: update fails fast, but the JSON-mode error lives on stderr only and uses generic `kind:"unknown"`/`type:"error"` instead of a plugin-specific not-found contract. **Required fix shape:** (a) define and consistently document stdout/stderr placement for JSON-mode lifecycle errors; (b) return a plugin-specific typed error with `kind:"plugin"` or `domain:"plugin"`, `action:"update"`, `status:"not_found"` or `code:"plugin_not_found"`, `plugin`, and optional `available_plugins[]`; (c) share missing-target error-envelope behavior across disable/update/uninstall and reconcile it with enable's timeout path; (d) add regression coverage proving `plugins update does-not-exist --output-format json` produces a typed plugin-not-found JSON contract on the documented stream. **Why this matters:** update is a maintenance/control-plane operation often run in automation. A stale plugin name should produce a predictable, domain-specific not-found result, not require callers to special-case stderr-only generic error envelopes after explicitly requesting JSON. Source: gaebal-gajae dogfood follow-up for the 23:00 nudge on rebuilt `./rust/target/debug/claw` `5eb1d7d8`; invalid hang PR #2894 was closed after repeated bounded repros returned exit 1 with JSON on stderr.