Document stderr-only session help JSON contract gap

Capture the dogfood evidence as a roadmap item so the stdout JSON error-envelope contract can be fixed and regression-tested later.\n\nConstraint: User requested exactly one ROADMAP.md-only item #340 from current origin/main.\nConfidence: high\nScope-risk: narrow\nTested: git diff --check; scripts/fmt.sh --check\nNot-tested: Runtime behavior unchanged; documentation-only roadmap entry.

ROADMAP.md

@@ -6277,3 +6277,5 @@ Original filing (2026-04-18): the session emitted `SessionStart hook (completed)
 338. **Top-level `help --output-format json` and resume-safe `/help --output-format json` use different payload fields for the same help surface (`message` vs `text`)** — dogfooded 2026-04-29 on current `origin/main` / workspace HEAD `24ccb59b` after rebuilding the actual debug binary with `cargo run --manifest-path rust/Cargo.toml --bin claw -- version --output-format json`; `./rust/target/debug/claw version --output-format json` reported embedded `git_sha` `24ccb59b`, matching the workspace. Running `./rust/target/debug/claw help --output-format json` returned a valid JSON object with keys `kind,message`, while `./rust/target/debug/claw --resume latest /help --output-format json` returned the same conceptual help surface with keys `kind,text`. Both are prose-only help payloads, but automation now has to special-case whether help was reached through the top-level command dispatcher or the resume-safe slash dispatcher before it can even locate the rendered help body. This is distinct from #325's broader structured-schema absence: the pinpoint here is a concrete JSON field-name contract drift between two help entrypoints that should be equivalent or explicitly versioned. **Required fix shape:** (a) define one canonical help JSON body field such as `message` or `text` and use it consistently across top-level `help`, slash `/help`, and resume-safe `/help`; (b) if backward compatibility requires both fields temporarily, emit both with identical contents plus a `schema_version` and deprecation metadata; (c) add regression coverage proving `claw help --output-format json` and `claw --resume latest /help --output-format json` expose the same top-level field contract and `kind=help`; (d) document whether slash-command JSON is intended to share schemas with top-level command JSON or carry its own explicit schema namespace. **Why this matters:** help JSON is the bootstrap discoverability surface for claws. If the same help concept moves its body between `message` and `text` depending on invocation path, every orchestrator needs brittle per-entrypoint parsers before it can inspect commands, flags, or resume safety. Source: gaebal-gajae dogfood in `/home/bellman/Workspace/claw-code` on 2026-04-29 using rebuilt `./rust/target/debug/claw`; proof commands showed top-level help JSON keys `kind,message` and resume-safe slash help JSON keys `kind,text` on the same rebuilt binary.
 
 339. **`/session delete` is not resume-safe while `/session list` is, making session GC impossible from `--resume` mode automation** — dogfooded 2026-04-30 by Jobdori on `24ccb59`. Running `claw --output-format json --resume latest /session list` succeeds and returns the full session list (10 sessions, all `workspace_dirty: true, abandoned: true`). Running `claw --output-format json --resume latest /session delete <id>` returns `{"command":"...","error":"unsupported resumed slash command","type":"error"}` — again using `"type"` not `"kind"` (#336 vocab violation). An automation lane that discovers abandoned sessions via `--resume` cannot delete any of them via the same path; it must spawn an interactive REPL session just to issue delete, breaking the machine-readable JSON surface contract. **Required fix shape:** (a) mark `/session delete` as resume-safe; (b) return `{"kind":"session_deleted","session_id":"<id>","path":"<deleted_path>"}` on success; (c) require `--force` only for dirty/active sessions; (d) add regression coverage. Source: Jobdori live dogfood, mengmotaHost, `24ccb59`, 2026-04-30.
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+340. **Resume-safe `/session help --output-format json` writes its primary JSON error envelope to stderr and uses `type` instead of the session JSON `kind` vocabulary** — dogfooded 2026-04-29 on current `origin/main` / rebuilt `./rust/target/debug/claw` with embedded `git_sha` `dc47482e`. Running `./rust/target/debug/claw --resume latest /session help --output-format json` wrote no stdout bytes, but wrote a JSON error object to stderr: `{"command":"/session help","error":"Unknown /session action ...","type":"error"}`. Meanwhile `/session list --output-format json` wrote valid stdout JSON with `kind=session_list`. The JSON output contract is therefore split across stderr for an error/help-ish action and switches vocabulary from `kind` to `type`; automation that reads stdout sees empty/non-JSON output and cannot handle errors consistently with successful session JSON responses. **Required fix shape:** (a) all `--output-format json` command responses, including resumed slash errors, should emit the primary JSON envelope on stdout; (b) use `kind:"error"` or a documented error schema consistently instead of an ad hoc `type` field; (c) reserve stderr prose for text mode or optional non-primary diagnostics, not the machine-readable envelope; (d) add a regression for `/session help` or an unsupported `/session` action under `--resume` proving stdout contains the structured JSON error envelope and stderr does not carry the only parseable payload. **Why this matters:** claws need one stdout JSON contract for both success and failure. If a help-ish session error is silently moved to stderr and shaped differently from `session_list`, orchestration lanes cannot distinguish an unsupported action from transport corruption or an empty response without bespoke stderr parsing. Source: gaebal-gajae dogfood follow-up for the 15:30 nudge on rebuilt `./rust/target/debug/claw` `dc47482e`.