plastic-intent-starting

# Intent Starting — board a session onto an intent Announce: "Boarding intent [ID] — [name]." `plastic-intent-starting` is the Start procedure. It boards a session onto one intent: take the lock FIRST, confirm the delivery state, ask **auto or guided ONCE**, board at the latest delivered station, then run the cycle to Done. The What → Why → How → Exec stations are the train track; Start boards the train, the ending procedure (~93) exits it. ## Precondition + trigger Fires when the user picks an intent to work, when an agent is told to continue a SPECIFIC intent, or on `continuing --intent {id}` (the `continuing` → `starting` router is 106's job; this skill is invokable standalone now). If the intent is **terminal** (Done / Abandoned in INDEX): report only. Take NO lock, run NO resume, do NOT reopen it. Summarize the outcome and ask what is next. Stop here. ## Lock FIRST (the spine) The lock is non-negotiable and comes before any mutating work. The ACTION-3 lock-gate enforces it: without a held lock, mutating writes to this active intent's dir are denied with "run /plastic-intent-starting to lock and begin". 1. **Ensure the intent is in INDEX `## Active`.** If it sits in `## Future`, activate it (move it to `## Active`, auto-commit) before arming. Creation precedes activation, so a brand-new What intent is activated here, then locked. 2. **Self-heal the lock state first.** Run: `ruby ~/.plastic/scripts/plastic-lock fix --intent-dir <STORE>/<dir>` This is th...