feat: initial ralph-workplan skill

Standalone Claude Code skill that ties a ralph loop to a workplan file.
Retires automatically when all tasks are done — no external dependencies.

- plugin/ralph-workplan.md      skill entrypoint
- plugin/scripts/check-done.sh  pre-start guard (reads workplan status)
- plugin/scripts/setup.sh       writes ralph state file with workplan-aware prompt
- install.sh                    copies plugin files to ~/.claude/plugins/
- workplan-spec.md              workplan file format reference
- README.md

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

plugin/ralph-workplan.md

@@ -0,0 +1,76 @@
+---
+description: "Start a Ralph loop tied to a workplan file — retires automatically when all tasks are done"
+argument-hint: "<workplan-file> [--max-iterations N]"
+allowed-tools: ["Read", "Bash(${CLAUDE_PLUGIN_ROOT}/scripts/check-done.sh:*)", "Bash(${CLAUDE_PLUGIN_ROOT}/scripts/setup.sh:*)"]
+hide-from-slash-command-tool: "true"
+---
+
+# Ralph Workplan
+
+Start a ralph loop driven by a workplan file. The loop retires automatically
+when all tasks in the workplan are marked done.
+
+## Usage
+
+```
+/ralph-workplan workplans/WP-0001-my-task.md
+/ralph-workplan workplans/WP-0001-my-task.md --max-iterations 15
+```
+
+The workplan file must follow the format described in `workplan-spec.md`
+(YAML frontmatter with `id`, `title`, `status` fields; tasks as fenced
+`task` code blocks with `id` and `status`).
+
+## Steps
+
+Parse `$ARGUMENTS` to extract:
+- `WORKPLAN_FILE` — the positional argument (required)
+- `MAX_ITERATIONS` — value after `--max-iterations` (default: 20)
+
+**Step 1 — Validate the workplan file exists**
+
+If the file does not exist:
+> "❌ Workplan file not found: $WORKPLAN_FILE"
+
+Stop.
+
+**Step 2 — Read the workplan frontmatter**
+
+Read `$WORKPLAN_FILE`. Extract from the YAML frontmatter:
+- `id` — workplan identifier
+- `title` — workplan title
+- `status` — current status
+
+**Step 3 — Guard: check if already done**
+
+Run:
+```bash
+"${CLAUDE_PLUGIN_ROOT}/scripts/check-done.sh" "$WORKPLAN_FILE"
+```
+
+Exit code 0 means the workplan is already done. If so:
+> "✅ Workplan $ID ('$TITLE') is already done — all tasks complete.
+>  Nothing to do. No ralph loop started."
+
+Stop.
+
+**Step 4 — Show current task summary**
+
+Count the task blocks in the file (fenced blocks with language tag `task`).
+Report:
+> "📋 $ID — $TITLE
+>  Tasks: X done, Y in progress, Z todo (N total)
+>  Starting ralph loop (max $MAX_ITERATIONS iterations)..."
+
+**Step 5 — Start the loop**
+
+Run:
+```bash
+"${CLAUDE_PLUGIN_ROOT}/scripts/setup.sh" \
+  "$WORKPLAN_FILE" "$ID" "$TITLE" "$MAX_ITERATIONS"
+```
+
+Then report:
+> "🔄 Ralph loop active. The loop will feed the workplan prompt back on every
+>  iteration. It retires when all tasks are done and the workplan status is
+>  updated to 'done' in the file."