docs(multi-agent): expand kickoff section with full spec→plans→launch workflow

docs/superpowers/MULTI-AGENT.md

@@ -114,9 +114,36 @@ In-flight messages are lost on restart. Any agent with unread messages should re
 
 ## Generating kickoff prompts
 
-Use the `multi-agent-kickoff` skill (in the `superpowers` plugin). It auto-discovers the spec and plans for the release, substitutes all placeholders including the relay paragraph, and writes files to `docs/superpowers/coordination/`.
+### Full workflow (spec → plans → kickoff)
 
-The skill reminder: run `tools/relay/start.sh` **before** opening the three Claude Code sessions — the MCP tools need the server to be up when each session initializes.
+**Step 1 — Write a spec**
+
+Run the `superpowers:brainstorming` skill. At the end it invokes `superpowers:writing-plans` for each dev stream. Each stream gets its own plan file in `docs/superpowers/plans/`. The spec lives in `docs/superpowers/specs/`.
+
+**Step 2 — Invoke the kickoff skill**
+
+Say anything like:
+- "kick off the multi-agent thing for v0.6.0"
+- "spin up PM and devs for this release"
+- "set up the three-terminal paradigm"
+
+The `multi-agent-kickoff` skill auto-triggers on those phrases. It will:
+
+1. Auto-discover the spec and plans by date/release label (asks to confirm if ambiguous)
+2. Generate `docs/superpowers/coordination/<release>-pm-prompt.md` and one `-dev-<letter>-prompt.md` per plan
+3. Inject the relay paragraph, branch names, worktree paths, test commands, and scope partitioning automatically from the plans and `CLAUDE.md`
+4. Commit the prompts and print launch instructions
+
+N>2 devs works automatically — 3 plans produces PM + Dev-A/B/C prompts.
+
+**Step 3 — Launch**
+
+```bash
+tools/relay/start.sh        # prints prompt file paths, starts relay server
+# open N+1 terminals, paste each prompt below its '---' line
+```
+
+The skill reminder: run `tools/relay/start.sh` **before** opening the Claude Code sessions — the MCP tools need the server up when each session initializes.
 
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