<purpose>
Add a new integer phase to the end of the current milestone in the roadmap. Automatically calculates next phase number, creates phase directory, and updates roadmap structure.
</purpose>

<required_reading>
Read all files referenced by the invoking prompt's execution_context before starting.
</required_reading>

<process>

<step name="parse_arguments">
Parse the command arguments:
- All arguments become the phase description
- Example: `/gsd-add-phase Add authentication` → description = "Add authentication"
- Example: `/gsd-add-phase Fix critical performance issues` → description = "Fix critical performance issues"

If no arguments provided:

```
ERROR: Phase description required
Usage: /gsd-add-phase <description>
Example: /gsd-add-phase Add authentication system
```

Exit.
</step>

<step name="init_context">
Load phase operation context:

```bash
_GSD_SHIM_NAME="gsd-tools.cjs"; _GSD_RUNTIME_ROOT="${RUNTIME_DIR:-$(git rev-parse --show-toplevel 2>/dev/null || pwd)}"; GSD_TOOLS="${_GSD_RUNTIME_ROOT}/gsd-core/bin/${_GSD_SHIM_NAME}"; _gsd_at() { for _p; do if [ -f "$_p" ]; then GSD_TOOLS="$_p"; return 0; fi; done; return 1; }; if _gsd_at "${_GSD_RUNTIME_ROOT}/gsd-core/bin/${_GSD_SHIM_NAME}" "${_GSD_RUNTIME_ROOT}/.claude/gsd-core/bin/${_GSD_SHIM_NAME}" "${_GSD_RUNTIME_ROOT}/.codex/gsd-core/bin/${_GSD_SHIM_NAME}"; then gsd_run() { node "$GSD_TOOLS" "$@"; }; elif unset -f gsd_run; _G="$(command -v gsd_run)"; then GSD_TOOLS="$_G"; gsd_run() { "$GSD_TOOLS" "$@"; }; elif _gsd_at "${CLAUDE_CONFIG_DIR:-$HOME/.claude}/gsd-core/bin/${_GSD_SHIM_NAME}" "${HERMES_HOME:-$HOME/.hermes}/gsd-core/bin/${_GSD_SHIM_NAME}" "${CURSOR_CONFIG_DIR:-$HOME/.cursor}/gsd-core/bin/${_GSD_SHIM_NAME}" "${CODEX_HOME:-$HOME/.codex}/gsd-core/bin/${_GSD_SHIM_NAME}" "${GEMINI_CONFIG_DIR:-$HOME/.gemini}/gsd-core/bin/${_GSD_SHIM_NAME}" "${COPILOT_CONFIG_DIR:-$HOME/.copilot}/gsd-core/bin/${_GSD_SHIM_NAME}" "${WINDSURF_CONFIG_DIR:-$HOME/.codeium/windsurf}/gsd-core/bin/${_GSD_SHIM_NAME}" "${AUGMENT_CONFIG_DIR:-$HOME/.augment}/gsd-core/bin/${_GSD_SHIM_NAME}" "${TRAE_CONFIG_DIR:-$HOME/.trae}/gsd-core/bin/${_GSD_SHIM_NAME}" "${QWEN_CONFIG_DIR:-$HOME/.qwen}/gsd-core/bin/${_GSD_SHIM_NAME}" "${CODEBUDDY_CONFIG_DIR:-$HOME/.codebuddy}/gsd-core/bin/${_GSD_SHIM_NAME}" "${CLINE_CONFIG_DIR:-$HOME/.cline}/gsd-core/bin/${_GSD_SHIM_NAME}" "${GROK_AGENTS_HOME:-$HOME/.agents}/gsd-core/bin/${_GSD_SHIM_NAME}" "${ANTIGRAVITY_CONFIG_DIR:-$HOME/.gemini/antigravity}/gsd-core/bin/${_GSD_SHIM_NAME}" "${OPENCODE_CONFIG_DIR:-${XDG_CONFIG_HOME:-$HOME/.config}/opencode}/gsd-core/bin/${_GSD_SHIM_NAME}" "${KILO_CONFIG_DIR:-${XDG_CONFIG_HOME:-$HOME/.config}/kilo}/gsd-core/bin/${_GSD_SHIM_NAME}"; then gsd_run() { node "$GSD_TOOLS" "$@"; }; else echo "ERROR: gsd-tools.cjs not found at $GSD_TOOLS and gsd_run is not on PATH. Run: npx -y @opengsd/gsd-core@latest --claude --local" >&2; exit 1; fi; GSD_IDENTITY_STATUS=unverified; case "$(gsd_run runtime-identity --raw 2>/dev/null || true)" in '{"packageName":"@opengsd/gsd-core"'*'}') GSD_IDENTITY_STATUS=ok;; esac; export GSD_IDENTITY_STATUS; [ "$GSD_IDENTITY_STATUS" = ok ] || echo "WARNING: \"$GSD_TOOLS\" did not prove it is @opengsd/gsd-core - it is either a different package or an @opengsd/gsd-core older than the runtime-identity verb. See docs/how-to/diagnose-a-foreign-gsd-tools.md" >&2; if [ -n "${CLAUDE_ENV_FILE:-}" ] && [ -n "${GSD_TOOLS:-}" ]; then printf "export PATH='%s':\"\$PATH\"\n" "${GSD_TOOLS%/*}" >> "$CLAUDE_ENV_FILE" 2>/dev/null || true; fi
INIT=$(gsd_run query init.phase-op "0")
if [[ "$INIT" == @file:* ]]; then INIT=$(cat "${INIT#@file:}"); fi
```

Check `roadmap_exists` from init JSON. If false:
```
ERROR: No roadmap found (.planning/ROADMAP.md)
Run /gsd:new-project to initialize.
```
Exit.
</step>

<step name="add_phase">
**Delegate the phase addition to `gsd_run query phase.add`:**

```bash
RESULT=$(gsd_run query phase.add "${description}")
```

The CLI handles:
- Finding the highest existing integer phase number
- Calculating next phase number (max + 1)
- Generating slug from description
- Creating the phase directory (`.planning/phases/{NN}-{slug}/`)
- Inserting the phase entry into ROADMAP.md with Goal, Depends on, and Plans sections

Extract from result: `phase_number`, `padded`, `name`, `slug`, `directory`.

**If result includes a `warning` field:** the description read as goal-shaped (long and/or multi-sentence) rather than title-shaped, and was written verbatim as the `### Phase N:` header. The phase was still created — surface the warning to the user and suggest a short title with the detail moved to `**Goal:**` in ROADMAP.md.
</step>

<step name="update_project_state">
Update STATE.md to reflect the new phase:

1. Read `.planning/STATE.md`
2. Under "## Accumulated Context" → "### Roadmap Evolution" add entry:
   ```
   - Phase {N} added: {description}
   ```

If "Roadmap Evolution" section doesn't exist, create it.
</step>

<step name="completion">
Present completion summary:

```
Phase {N} added to current milestone:
- Description: {description}
- Directory: .planning/phases/{phase-num}-{slug}/
- Status: Not planned yet

Roadmap updated: .planning/ROADMAP.md

---

## ▶ Next Up — [${PROJECT_CODE}] ${PROJECT_TITLE}

**Phase {N}: {description}**

`/clear` then:

`/gsd:plan-phase {N}`

---

**Also available:**
- `/gsd-add-phase <description>` — add another phase
- Review roadmap

---
```
</step>

</process>

<success_criteria>
- [ ] `gsd_run query phase.add` executed successfully
- [ ] Phase directory created
- [ ] Roadmap updated with new phase entry
- [ ] STATE.md updated with roadmap evolution note
- [ ] User informed of next steps
</success_criteria>