runtime_bridge Compat-Delegate Classification (WP02 — FR-003 / #2561)

Status: authoritative classification for the Lane-0 deshim chain (WP02 classify → WP03/WP04 repoint → WP18 delete). WP02 makes zero src edits; this artifact + the per-name evidence in tasks/WP02-runtime-bridge-delegate-deletion.md history + the FR-016 row in tracer-design-decisions.md are the classification of record.

Scope

~416 setattr(runtime_bridge…) / "runtime.next.runtime_bridge.<name>" occurrences across 53 test files (WP03 ~241 in tests/next + WP04 ~168 elsewhere). Of the runtime_bridge.py public+private surface, 45 pure-forwarding compat-delegate candidates were audited = 37 native def/class "Thin compat delegate" symbols + 8 plain self-alias re-export imports.

Verdict: 0 deletable pre-repoint

A grep-only pass first flagged 5 apparently-zero-reference names (_extract_wp_heading, _collect_requirement_refs_for_section, _iter_requirement_refs, _requirement_inline_refs_suffix, _is_requirement_heading). Deleting them turned tests/runtime/test_bridge_cores.py::test_untracked_parse_helpers_are_identity_reexports RED (AttributeError) — it asserts getattr(rb, name) is getattr(cores, name) for that exact tuple, required by test_bridge_compat_surface.py's FROZEN exact-baseline (test_guard_b_identity_reexport_for_relocated_symbols). A dependency grep cannot see an identity-equality assertion driven by a name-list variable. Reverted; baseline green (121 passed on the 3 owned compat-surface files; 628 passed / 1 skipped on full tests/runtime + test_no_dead_symbols.py).

Categories (drives WP03/WP04/WP18)

Category	Count	Disposition	Owner
Canonical __all__ surface (get_or_start_run, build_operational_context_for_claim)	2	Permanently kept	—
Native forwarding delegates still patched/imported via the OLD runtime_bridge.<name> path	35	Repoint-then-delete — WP03 repoints tests/next, WP04 the rest; WP18 deletes the façade delegate once grep=0	WP03/WP04 → WP18
Live production cross-seam _rb.<name> deps (_retrospective_blocks_completion, _composition_dispatch_inputs, _has_generated_docs)	3	Call-site refactor + delete — WP18 refactors the 3 call-sites to import the seam leaf directly, then deletes the façade delegate	WP18

Category counts sum to 40 named dispositions here; the residual of the 45 audited candidates are the self-alias re-export imports folded into the "repoint-then-delete" set (they resolve via the same runtime_bridge.<name> path). Per-name evidence: WP02 add-history (see the WP02 task file history).

The 3 production call-sites (for WP18)

• _retrospective_blocks_completion — defined runtime_bridge_retrospective.py:381; called runtime_bridge_engine.py:249 as _rb._retrospective_blocks_completion(policy).
• _composition_dispatch_inputs — defined runtime_bridge_composition.py:299; trace its _rb. / in-module call-site before deleting the façade delegate.
• _has_generated_docs — defined runtime_bridge_composition.py:408; consumed via a live _rb._has_generated_docs lookup (runtime_bridge_composition.py:~414).

Ordering constraint (why WP18 exists)

WP03/WP04 depend on WP02, so WP02 cannot accept the reds its original prompt anticipated without breaking the serial chain. Deletion was therefore re-sequenced OUT of WP02 into WP18 (deps WP04), which runs the repoint-THEN-delete residue: delete the repointed forwarders, refactor the 3 call-sites, and update the frozen test_bridge_compat_surface.py baseline. NFR-001: WP01's dynamic-access-aware gate proves each deletion dead.