docs: establish integrated project memory

.project-docs/05-agent-entry/concurrent-task-gate.md

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+# Concurrent Task Gate
+
+Complete this gate before the Planning Gate.
+
+## Invariants
+
+- One active task owns one worktree.
+- Concurrent tasks use different branches and worktrees.
+- Never stash, reset, move, delete, or adopt unknown work automatically.
+- Feature tasks write only their own task record and uniquely named supporting records.
+- Keep the active task record present until ownership is released.
+- Treat `start`, `touch`, `complete`, and `release` as serialized registry transactions; lock timeout or malformed registry state blocks the gate.
+- Feature-task write boundaries in this gate supersede legacy instructions to update shared or canonical project documents.
+
+## Required Output
+
+- Task ID:
+- Mode: Feature | Integration
+- Branch:
+- Worktree:
+- Base commit:
+- Ownership result: Claimed | Resumed | Isolated | Blocked
+- Other active local tasks:
+
+## Block Conditions
+
+- The worktree belongs to another active task and isolation did not succeed.
+- An unowned worktree contains staged, unstaged, or untracked changes.
+- No reliable committed base was selected for a new worktree.
+- The runtime cannot keep later Git and file operations rooted in the isolated worktree.