<purpose>
Lightweight codebase assessment. Spawns a single gsd-codebase-mapper agent for one focus area,
producing targeted documents in `.planning/codebase/`.
</purpose>

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

<available_agent_types>
Valid GSD subagent types (use exact names — do not fall back to 'general-purpose'):
- gsd-codebase-mapper — Maps project structure and dependencies
</available_agent_types>

<process>

## Focus-to-Document Mapping

| Focus | Documents Produced |
|-------|-------------------|
| `tech` | STACK.md, INTEGRATIONS.md |
| `arch` | ARCHITECTURE.md, STRUCTURE.md |
| `quality` | CONVENTIONS.md, TESTING.md |
| `concerns` | CONCERNS.md |
| `tech+arch` | STACK.md, INTEGRATIONS.md, ARCHITECTURE.md, STRUCTURE.md |

## Step 1: Parse arguments and resolve focus

Parse the user's input for `--focus <area>`. Default to `tech+arch` if not specified.

Validate that the focus is one of: `tech`, `arch`, `quality`, `concerns`, `tech+arch`.

If invalid:
```
Unknown focus area: "{input}". Valid options: tech, arch, quality, concerns, tech+arch
```
Exit.

## Step 2: Check for existing documents

```bash
INIT=$(gsd-sdk query init.map-codebase 2>/dev/null || echo "{}")
if [[ "$INIT" == @file:* ]]; then INIT=$(cat "${INIT#@file:}"); fi
```

Look up which documents would be produced for the selected focus (from the mapping table above).

For each target document, check if it already exists in `.planning/codebase/`:
```bash
ls -la .planning/codebase/{DOCUMENT}.md 2>/dev/null
```

If any exist, show their modification dates and ask:
```
Existing documents found:
  - STACK.md (modified 2026-04-03)
  - INTEGRATIONS.md (modified 2026-04-01)

Overwrite with fresh scan? [y/N]
```

If user says no, exit.

## Step 3: Create output directory

```bash
mkdir -p .planning/codebase
```

## Step 4: Spawn mapper agent

Spawn a single `gsd-codebase-mapper` agent with the selected focus area:

```
Task(
  prompt="Scan this codebase with focus: {focus}. Write results to .planning/codebase/. Produce only: {document_list}",
  subagent_type="gsd-codebase-mapper",
  model="{resolved_model}"
)
```

## Step 5: Report

```
## Scan Complete

**Focus:** {focus}
**Documents produced:**
{list of documents written with line counts}

Use `/gsd-map-codebase` for a comprehensive 4-area parallel scan.
```

</process>

<success_criteria>
- [ ] Focus area correctly parsed (default: tech+arch)
- [ ] Existing documents detected with modification dates shown
- [ ] User prompted before overwriting
- [ ] Single mapper agent spawned with correct focus
- [ ] Output documents written to .planning/codebase/
</success_criteria>