AGENTS.md: mirror lab memo-trigger wording in session-startup §2

Keep the session-startup pre-flight checklist in sync with the lab repo
(lab/AGENTS.md §Session startup, step 2). Clarify that MEMORY.md index
lines are triggers, not summaries — open memos whose topic touches the
work you're about to do, before the first action in that area.

Mirror of lab@fa1a709 per the shared <!-- mirrored --> comment in this
file and the matching comment in lab/AGENTS.md. Keeps the two AGENTS.md
chains in lockstep across the sibling repos.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: is-primary-dev

AGENTS.md

@@ -49,7 +49,7 @@ The merge-to-master sequence (`git switch master && git merge --no-ff <feature>
 Pre-flight checklist before any work in a new session:
 
 1. **Read AGENTS.md** (auto-loaded via `CLAUDE.md` → `@AGENTS.md`).
-2. **Scan `MEMORY.md`** for topic-relevant entries; read individual `memory/*.md` entries on demand.
+2. **Scan `MEMORY.md`** and **open every memo whose topic touches the work you're about to do**, before the first action in that area. The index lines are *triggers*, not summaries — a one-line description cannot encode a precedence order, a procedure, or a wrapper subcommand name. Re-scan when you enter a new work phase and open anything that now applies. Treat a memo marked **OPEN before ...** in the index as mandatory for that phase.
 3. **Create/switch to a session branch** via `agent-helpers/safe-agent-action.sh session-start <plan-name>`. Plan file basename (without `.md`) is the branch name.
 4. **Use the wrapper from command #1.** No bare git, no bare grep, no subagents shelling out.