ah-0ge.2 Parent auto-Block/unblock join on child completion Past Stand

The join half of the delegation loop, per SPEC §14.4 'parent auto-Block/unblock'. When X spawns children it parks in the Blocked bucket — which already exists as a parked bucket that never claims and never kills (SPEC:174) — and returns to Ready when all children reach a terminal state. Needs a parent link (tasks.parent_id in internal/store/schema.sql, or Vikunja task relations) plus somewhere to hold each child's result for the resume payload.
UNSPECIFIED IN THE SPEC AND NEEDS A DECISION: partial failure. Y done, Z failed — does X resume with the failure reported, bounce to Failed, or go to Triage? §14 says auto-unblock but not what unblock means when a child died.

X with children Y,Z sits in Blocked while either runs and returns to Ready only once both are terminal; the partial-failure path is decided and covered by a transitions test.

COMPLETED 2026-07-17 together with ah-0ge.3 (they were inseparable — see prior note). The full block→wait→resume join is implemented and tested.

STATE MODEL: 'blocked' promoted to a real domain.State (7 states now). domain.States/Valid/CanClaim/CanonicalBuckets updated; BucketBlocked const removed (blocked is a state, not a parked bucket); triage/question remain parked. reconcile iterate() routes the blocked bucket to a new handleBlocked.

BEHAVIOR: a successful run that validly delegates now PARKS the parent in Blocked (delegateAndBlock) instead of In Review; children are created in target_bucket (triage=human-gated, ready=full-auto). handleBlocked resumes the parent (new attempt, resumeParent) once EVERY child reaches a terminal bucket (in_review/failed/done/cancelled; a vanished child counts terminal to avoid deadlock). Resume re-runs the role prompt + an appended 'Delegated work completed' section reporting each child's outcome and instructing 'do not re-delegate'. Child-done threshold = In Review (decision). Partial failure = resume-and-report; agent may retry (decision), bounded by MaxPerRun as a per-parent LIFETIME cap (existing ChildIDsOf count + requested) so retries can't loop forever. Depth bounded by MaxGeneration.

Tests: domain (7 states); reconcile (spawn→blocks, resume-when-children-finish incl. failed child in prompt, waits-while-pending, + updated ah-0ge.1 spawn/reject tests); store migration/lineage. Full unit suite + e2e green under -mod=readonly. SPEC §9-pseudocode, state model, and §12 updated.

NOTE/deviation: resume is a fresh attempt in the parent's existing worktree (which holds its committed work) + resume prompt, NOT a literal 'pi --session' continuation — pi session-file mechanics weren't verifiable here, and the worktree+prompt path is robust and correctness-equivalent for avoiding re-delegation. True --session continuation is a possible future optimization (see ah-0ge.3).