02 — All-documents Tree Build (runtime/180)

Candidate selection — live discovery, no hardcoded id

runtime/180 generalises runtime/170: where 170 selected the single richest document, 180 discovers every buildable flat draft IU across every document by live query and builds them all in one atomic transaction. A child is buildable iff it is flat (parent_or_container_ref IS NULL), draft, and a sibling exists at the canonical_address-derived parent (regexp_replace(addr,'-[^-]+$','')) in the same document.

B0 cross-document survey:

doc_code	buildable	flat_total
DIEU-28	14	27
DIEU-32	12	23
DIEU-35	0	17 (already built by runtime/170)

No document code and no IU id is baked into runtime/180; the test test_180_has_no_hardcoded_doc_or_id enforces this.

Batch execution

One atomic BEGIN … COMMIT. The structure-op gate is opened and closed inside the same transaction. Pairs ordered (doc_code, canonical_address) so a parent piece is nested before its sub-piece. For every buildable reparent: fn_iu_structure_op_plan → _apply → _verify. Any non-ok RAISEs and rolls back.

runtime/180: docs=2 applied=26 already_enacted=0 iu_event_outbox 18->44

Post-batch verification (B1–B7, in-transaction)

Check	Result
B1 ops	reparent_piece / enacted = 45 (1×140 + 18×170 + 26×180)
B2 depth	depth 0 = 113, depth 1 = 42, depth 2 = 3 (Σ = 158)
B3 consistency	iu_tree_path 158 = v_iu_tree 158 = live IU 158
B4 relation	active contains = 45, nested IU = 45
B5 events	event_outbox structure_op_applied = 44
B6 per-doc	DIEU-28 14 nested/13 flat; DIEU-32 12/11; DIEU-35 19/17
B7 gate	iu_core.structure_ops_enabled = false (layer inert)

Independent verification — runtime/130 (read-only)

S5 iu_structure_operation=45 iu_relation=45 iu_tree_path=158, S6 tree consistency 158=158=158 counts_agree=t, S8 stranded_midflight=0 enacted_terminal=45 rolled_back_terminal=0.

Rollback / compensation readiness

runtime/rollback/180 reverses the whole batch by actor iu_core_runtime_180 (reverse canonical order) behind the gate. Per-op fn_iu_structure_op_rollback is compensation-snapshot-driven. Each op individually reversible.