fix(phase): unify phase-dir naming via shared helper across creation paths (#3287) (#3292)

* test: phase-dir prefix parity across creation paths (#3287 RED)

Add failing tests asserting that init.phase-op and init.plan-phase
expose expected_phase_dir with the project_code prefix when the phase
directory does not yet exist — matching the prefix applied by phase.add.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix(phase): unify phase-dir naming via shared getPhaseDirName helper (#3287)

Both init.phase-op (discuss-phase workflow) and init.plan-phase
(plan-phase workflow) now compute expected_phase_dir — the canonical
directory name including the project_code prefix when set — and expose
it in their JSON bundle.

Workflow fallback mkdir calls are updated to use ${expected_phase_dir}
instead of constructing the path from padded_phase + phase_slug, which
was missing the project_code prefix.

This eliminates the two-headed naming convention where phase.add/insert
produced XR-01-foundation/ while the first-touch paths produced
01-foundation/ for the same project.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* refactor(phase): apply project_code prefix in scaffold phase-dir (#3287)

Audit finding: phase.scaffold (CJS commands.cjs + SDK phase-lifecycle.ts)
also constructed phase dir names without project_code prefix.

Both implementations now read config.project_code and apply the same
prefix logic as phase.add/phase.insert.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* changeset: pr=3292 for #3287

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* docs(changelog): add entry for #3287 phase-dir prefix parity fix

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -8,6 +8,7 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 ### Fixed
 
+- **`/gsd-discuss-phase` and `/gsd-plan-phase` first-touch creation now apply `project_code` prefix consistently with `phase.add`/`phase.insert`** — projects with `project_code` set in `.planning/config.json` no longer accumulate a two-headed naming convention (`01-foundation/` mixed with `XR-02.1-spike/`). `init.phase-op` and `init.plan-phase` now expose `expected_phase_dir` (with prefix) in their JSON bundle; workflow fallback mkdir calls use this value instead of constructing the path from `padded_phase`+`phase_slug`. `phase.scaffold phase-dir` (CJS and SDK) also fixed. (#3287)
 - **`buildStateFrontmatter` now counts nested `plans/<N>-PLAN-<NN>-<slug>.md` files** — repos using the nested layout (post-#3139) no longer get `progress.*` counters silently overwritten downward on every state mutation. Sibling fix to #3115/#3139/#3191. (#3261)
 
 ## [1.41.0](https://github.com/gsd-build/get-shit-done/compare/v1.40.0...v1.41.0) - 2026-05-07