docs: add Trellis planning and project specs

.agents/skills/trellis-start/SKILL.md

@@ -0,0 +1,64 @@
+---
+name: trellis-start
+description: "Initializes an AI development session by reading workflow guides, developer identity, git status, active tasks, and project guidelines from .trellis/. Classifies incoming tasks and routes to brainstorm, direct edit, or task workflow. Use when beginning a new coding session, resuming work, starting a new task, or re-establishing project context."
+---
+
+# Start Session
+
+Initialize a Trellis-managed development session. This platform has no session-start hook, so manually load the equivalent compact context by following these steps.
+
+---
+
+## Step 1: Current state
+Identity, git status, current task, active tasks, journal location.
+
+```bash
+python3 ./.trellis/scripts/get_context.py
+```
+
+If this output includes a line beginning `Trellis update available:`, copy the full line verbatim when summarizing session context. Do not shorten operational command hints.
+
+## Step 2: Workflow overview
+Compact Phase Index, request triage rules, planning artifact contract, and the step-detail command.
+
+```bash
+python3 ./.trellis/scripts/get_context.py --mode phase
+```
+
+Full guide in `.trellis/workflow.md` (read on demand).
+
+## Step 3: Guideline indexes
+Discover packages + spec layers, then read each relevant index file.
+
+```bash
+python3 ./.trellis/scripts/get_context.py --mode packages
+cat .trellis/spec/guides/index.md
+cat .trellis/spec/<package>/<layer>/index.md   # for each relevant layer
+```
+
+Index files list the specific guideline docs to read when you actually start coding.
+
+## Step 4: Decide next action
+From Step 1 you know the current task and status. Check the task directory:
+
+- **Active task status `planning` + no `prd.md`** → Phase 1.1. Load the `trellis-brainstorm` skill.
+- **Active task status `planning` + `prd.md` exists** → stay in Phase 1. Lightweight tasks can be PRD-only; complex tasks need `design.md` + `implement.md`. Load the relevant Phase 1 step detail before `task.py start`.
+- **Active task status `in_progress`** → Phase 2 step 2.1. Load the step detail:
+  ```bash
+  python3 ./.trellis/scripts/get_context.py --mode phase --step 2.1 --platform codex
+  ```
+- **No active task** → classify first. For simple conversation / small task, ask only whether this turn should create a Trellis task. For complex work, ask whether you may create a Trellis task and enter planning. If the user says no, skip Trellis for this session.
+
+---
+
+## Skill routing (quick reference)
+
+| User intent | Skill |
+|---|---|
+| New feature / unclear requirements | `trellis-brainstorm` |
+| About to write code | `trellis-before-dev` |
+| Done coding / quality check | `trellis-check` |
+| Stuck / fixed same bug multiple times | `trellis-break-loop` |
+| Learned something worth capturing | `trellis-update-spec` |
+
+Full rules + anti-rationalization table in `.trellis/workflow.md`.