Add resolvePlanningDir() and buildPaths() to core.cjs, then thread
the paths object through all 11 modules. In flat mode (no workstreams
directory), all paths resolve identically to the previous hardcoded
.planning/ paths — zero behavior change verified via init progress
diff.

- core.cjs: new resolvePlanningDir(), buildPaths(), toPosixPath()
- gsd-tools.cjs: parse --ws flag, build paths, pass to all dispatches
- All 10 lib modules: accept optional paths param, use p.* instead
  of hardcoded path.join(cwd, '.planning', ...)

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

Add lib/workstream.cjs with four commands:
- workstream create <name>: creates .planning/workstreams/{name}/ with
  STATE.md and phases/ scaffolding. On first create, auto-migrates
  existing flat .planning/ files (ROADMAP, STATE, REQUIREMENTS, phases/)
  into a named workstream based on current milestone.
- workstream list: enumerates all workstreams with status, phase counts
- workstream status <name>: detailed status for a single workstream
- workstream complete <name>: archives workstream to milestones/

Migration is transparent — first workstream create detects flat mode,
moves scoped files to workstreams/{milestone-slug}/, leaves shared
files (PROJECT.md, config.json, todos/, research/) in place.

Backward compat verified: agent42 flat-mode output unchanged.

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

Add workstream flag passthrough to core workflow files:
- references/workstream-flag.md: shared pattern doc for WS extraction
- workflows/execute-phase.md: WS init, dynamic paths in subagent
  <files_to_read> and commit --files
- workflows/execute-plan.md: WS init, dynamic phase_dir paths,
  per-workstream agent tracking files
- workflows/new-milestone.md: WS init, dynamic paths in researcher/
  roadmapper subagent prompts and all commit commands

Remaining workflows (transition, discuss-phase, etc.) need the same
treatment in a follow-up — core agent still running.

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

… updates

Adds --ws flag extraction and dynamic path variables to three more
core workflows. execute-plan.md gets additional edits beyond the
partial commit.

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

Adds --ws flag extraction and ${GSD_WS} passthrough to all gsd-tools.cjs
invocations across 24 workflow files. Replaces hardcoded .planning/
paths with init-derived variables (state_path, roadmap_path, phase_dir,
etc.) for workstream-scoped resources. Shared paths (PROJECT.md,
milestones/, codebase/, config.json, todos/) left unchanged.

4 files correctly skipped (no gsd-tools calls): discovery-phase.md,
help.md, list-phase-assumptions.md, update.md.

Backward compat verified: init progress output byte-identical to baseline.

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

- Active workstream detection: .planning/active-workstream file
  auto-detected when --ws flag not passed
- workstream set/get commands: persist and query active workstream
- workstream progress: cross-workstream summary with phase counts,
  plan counts, and progress percentages
- Commit prefixes: [ws-name] prepended to commit messages when
  workstream is active

New functions: getActiveWorkstream(), setActiveWorkstream() in core.cjs
New commands: workstream set|get|progress in workstream.cjs
Modified: cmdCommit() accepts ws param for prefix injection

Backward compat verified: init progress output identical in flat mode.

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

Adds Step 0 (Workstream Detection) that checks if an existing milestone
is in-flight before starting a new one. If so, offers parallel workstream
creation with automatic migration of existing flat files. Handles three
cases: flat mode with conflict, already in workstream mode, and greenfield.

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

…s quoting

- new-milestone Step 0: ask milestone name before workstream create (slug needs name)
- workstream create: auto-set active workstream (no separate set command needed)
- complete-milestone: offer workstream archival after milestone ships
- execGit: use execFileSync to avoid shell quoting issues with brackets on Windows

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

Blockers fixed:
- cmdWorkstreamComplete now clears active-workstream file
- migrateToWorkstreams rolls back on partial failure
- resolvePlanningDir no longer silently falls back to phantom 'default' ws
- new-milestone Step 7 no longer overwrites GSD_WS set by Step 0
- complete-milestone complete_workstream step rewritten to avoid double-archive

Code quality:
- Same-day archive collision prevention (suffix counter)
- Failed create no longer blocks retry (check STATE.md not just dir)
- generate-slug guards against empty result
- Redundant inline requires removed from workstream.cjs
- Path-traversal validation added to migrateToWorkstreams

Workflow gaps (14 files):
- 7 files now have bash WS extraction block (were using ${GSD_WS} undefined)
- 7 files prose-only extraction replaced with standard bash block

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

…gaps

- isGitIgnored migrated to execFileSync (consistent with execGit fix)
- cmdWorkstreamComplete: archive loop now has rollback on failure
- cmdWorkstreamComplete/Status: path-traversal validation on name param
- quick.md: add missing WS extraction block (last workflow gap)
- plan-phase.md: auto-advance Task spawn now passes ${GSD_WS}
- complete-milestone.md: simplify redundant WS_NAME re-extraction

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

Document the parallel workstreams feature — how to run multiple Claude Code
instances on independent features with isolated planning state.

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