feat(#3146): resolve gsd_run so workflows cannot reach a foreign gsd-tools (#3831)

* feat(#3146): resolve gsd_run so workflows cannot reach a foreign gsd-tools

The predecessor package get-shit-done-cc publishes a colliding gsd-tools bin whose phases.clear DELETES where this package's ARCHIVES, and both print success-shaped output against a gitignored .planning/ -- which is how #3129 cost a user 43 phase directories with no error and nothing recoverable from git.

The launcher's PATH branch now resolves gsd_run, published only by this package and self-locating via its own symlink chain to the sibling shim, instead of the colliding gsd-tools. A foreign handler becomes unreachable from PATH, and when no gsd_run is reachable the resolver fails closed rather than falling back -- that fallback was the vulnerability. This is smaller than the branch it replaces, which matters: the preamble is inlined into 113 shipped files and agents/gsd-verifier.md sits 2 bytes under a red-line size cap.

unset -f gsd_run leads the preamble so a re-source is idempotent. Without it, command -v finds the shell function, returns a bare name, and the resolver falls through to an exit 1 that kills a sourced caller's shell.

Adds gsd-tools runtime-identity, a manual diagnostic reporting this runtime's package coordinates over the baked package-identity (#498) and readHostVersion, with a strict total classifier: only a JSON object with an exact packageName verifies, since JSON.parse admits 0/"str"/[]/null/true.

An inlined identity assertion was built and reviewed first, then withdrawn -- it breaks five frozen size ceilings and no assertion fits in 2 bytes.

Closes #3146

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* fix(#3146): stop sync:launcher relocating a deliberate preamble placement

Pre-existing defect, surfaced by this PR because sync is a no-op unless the snippet content actually changes. transformFile inserts the preamble into the first block that CALLS gsd_run, but gsd-core/workflows/explore.md deliberately places it in a bootstrap-only block that DEFINES gsd_run without calling it -- its own comment explains why: declining the research offer must not leave Step 5's commit call unbootstrapped. Stripping empties that block of calls, so the preamble migrated forward and broke the define-before-use invariant tests/explore-command.test.cjs pins.

Reproduced on a pristine origin/next checkout with the base snippet and base file, so this was not introduced here. The insertion target now honours a block that already carried the preamble, falling back to the first calling block for files that have none yet. Adds a behavioral regression test over a two-block fixture.

Also updates three runtime-launcher-parity tests that pinned the removed PATH fallback to gsd-tools. Their intent is preserved -- the PATH stub is renamed gsd_run so it is reachable by the new resolver, and the RUNTIME_DIR-wins test still asserts the stub is never invoked. Fixture shebangs move to an absolute /bin/sh, because the fixture PATH is deliberately restricted and #!/usr/bin/env sh could not resolve.

Refs #3146

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* chore(#3146): backfill changeset PR number

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* docs(#3146): document the FEATURES.md section-numbering practice

The monotonically increasing section number in docs/FEATURES.md is the most frequent merge-conflict source in this repo, and it has TWO conflict cells, not one: the ### N. heading and the hand-maintained table of contents. Two PRs adding differently numbered features still collide on the TOC, so renumbering alone does not make a branch safe. This branch alone was renumbered 165 -> 166 -> 167 -> 168 across successive rebases.

Adds a CONTRIBUTING section stating the practice: allocate the number last, never pre-emptively renumber, take max+1 after a rebase and update the TOC in the same commit, and never renumber someone else's section. Fork contributors are told explicitly they may leave the number to a maintainer at merge rather than chasing the counter. Agents are told to lease the allocation and to include the file in their published touched set.

Records the durable fix as planned rather than pretending it exists: FEATURES.md should be generated from per-feature fragments the way CHANGELOG.md is generated from .changeset/, and the way tests/emitted-drift-acks/ works (#2914).

Also renumbers this branch's own section to 168, leaving 167 to the PR already in flight.

Refs #3146

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

---------

Co-authored-by: sim <sim@local>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

CONTEXT.md

@@ -35,6 +35,9 @@ Module owning phase-directory search and location: active-phase discovery agains
 ### Plan Dependency Graph Module
 Module owning the single halt-propagation engine over a plan's `depends_on` DAG (#2830). **Domain term: _halted_** — a plan that reached a designed stop (a gate failure, a spike concluding without expanding, or any other intentional non-completion) and wrote a SUMMARY recording that fact via `status: halted` in its frontmatter, as opposed to `status: complete` (ordinary finish) or no SUMMARY at all (not yet attempted). **Domain term: _blocked_** — a plan whose `depends_on` chain reaches a halted plan, directly or transitively; distinct from merely _incomplete_ (no SUMMARY yet) — an ordinary in-progress/not-yet-started dependency does not block. `computeHaltPropagation(nodes: {id, resolvedDependsOn, halted}[])` performs exactly one Kahn's-algorithm topological pass and returns `{order, visited, blockedBy}`, where `blockedBy` maps a plan id to the de-duplicated set of halted plan ids transitively upstream of it (diamond-safe, any depth). This is the SHARED engine both of the two independent "which plans are incomplete" readers call — `phase.cts`'s wave-grouping (`cmdPhasePlanIndex`) and `phase-locator.cts`'s phase-location primitive (`searchPhaseInDir`) — so the two-implementation divergence that caused #2830 (one parsed `depends_on` for waves only, the other never parsed it at all) cannot recur: each caller resolves its own raw `depends_on` tokens to canonical ids before calling in, but the graph traversal itself exists in exactly one place. Pure — no I/O, no config; each caller does its own file reads (a plan's frontmatter, a completed plan's SUMMARY `status`) and fails open (treats an unreadable/malformed file as "not halted"/"no deps") rather than throwing. Source of truth: `gsd-core/bin/lib/plan-dependency-graph.cjs` (generated from `src/plan-dependency-graph.cts`).
 
+### Runtime Identity Module
+Module owning this package's runtime identity surface and the resolver preference that keeps a shipped workflow off a foreign handler (#3146). **Domain term: _colliding bin_** — a binary name published by more than one package with different semantics behind it; here `gsd-tools`, published by both this package and the predecessor `get-shit-done-cc` (verified against 1.42.3: `bin.gsd-tools → bin/gsd-sdk.js`), whose `phases.clear` **deletes** where this package's **archives**, both printing success-shaped output against a gitignored `.planning/` (#3129). **The fix is resolution, not detection.** `_runtime-launcher.snippet.sh`'s PATH branch resolves **`gsd_run`** — published only by this package, and self-locating via its own symlink chain to the `gsd-tools.cjs` beside it — instead of the colliding `gsd-tools`, so a foreign handler is unreachable from PATH; when no `gsd_run` is reachable the resolver fails closed through its remaining path-based branches rather than falling back to an arbitrary `gsd-tools`. An `[ -x ]` guard on the probe result is load-bearing: on a second source of the preamble `command -v gsd_run` finds the shell FUNCTION and returns the bare string `gsd_run`, which would otherwise define the function in terms of itself. **Why not an inlined assertion:** an identity check in the preamble was built, reviewed, and abandoned — the preamble is inlined into 113 shipped files and several sit within single-digit bytes of frozen size ceilings (`agents/gsd-verifier.md` had 2 bytes of headroom; the LARGE cap is a red line, and #3645 freezes `gsd-planner.md`), so no assertion of any terseness fits. The resolver change is 16 bytes SMALLER than what it replaced. The module still exports the identity surface backing the `runtime-identity` verb: `classifyIdentityProbe` (pure, total — `(stdout, exitCode, spawnFailed, timedOut)` → `ok`/`identity_mismatch`/`no_identity_verb`/`unparseable`/`probe_failed`; strict because `JSON.parse` admits `0`/`"str"`/`[]`/`null`/`true` and a truthiness test would verify `[]`), `buildIdentityPayload` over baked `package-identity.cjs` coordinates plus `readHostVersion()`, and `explainVerdict`. That verb is a manual diagnostic, not an automatic gate. Source of truth: `gsd-core/bin/lib/runtime-identity.cjs` (generated from `src/runtime-identity.cts`).
+
 ### Dispatch Policy Module
 Module owning dispatch error mapping, fallback policy, timeout classification, and CLI exit mapping contract.