**Status:** PHASE 3 COMPLETE 2026-04-24. All 6 batches landed + pushed

to SonicField/cpython phoenix-asm-integration. Per-batch dual-arch +

per-bench floor + W45 §3.5 BUILD MODE all green.

**Phase 3 design choice (per pythia #103 + theologian 00:59:37Z +

supervisor 00:59:39Z):** Class B-kept is a TRANSITIONAL disposition,

not the final shape. Bridge surface paid as Phase 3 foundation cost;

Tier 8 pilot validates the migrate-arm by porting one Class B field

to pure C (per docs/tier8-class-b-cport-migrate-arm-spec.md).

| Batch | Commit | NET | Description |

|-------|--------|-----|-------------|

| 1 | c905827742 | +140L | PhxHirBuilderState foundation + parseExceptionTable port + 3 bridges |

| 2 | 1343895045 | +80L | findExceptionHandler port + exception_table_ Class B-kept closure (read+write bridges) |

| 3 | b92d85e751 | -13L | pending_b2_blocks_ DEAD-STATE delete (no writers post-W26 refactor) |

| 4 | b44a5143cc | +27L | block_map_ Class B-kept closure (blocks_lookup_cpp + hir_c_api rewire) |

| 5 | 782d56d0c6 | +9L | static_method_stack_ rename _pop_c → _pop_cpp (consistency) |

| 6 | 7971941afe | +14L | temps_ alloc_stack rename (75-site sed) — all 5 Class B disposed |

**Cumulative NET: +257L** (foundation cost).

**Push count:** 18 → 24 today; full session 4 + 24 = 28 push events

across the multi-day workstream (inclusive of pre-Phase 3 Phase 1

burndown + W44/W45/§3.5 falsifier infra).

All 5 Class B HirBuilder members disposed:

| Member | Disposition | Closure mechanism |

|--------|-------------|--------------------|

| `exception_table_` (std::vector) | CLOSED via Batch 2 | 4 bridges: push_cpp + size_cpp + entry_cpp + find_c (read+write) |

| `block_map_` (std::unordered_map ×2) | CLOSED via Batch 4 | 1 bridge: blocks_lookup_cpp + hir_c_api rewire |

| `pending_b2_blocks_` (std::vector) | DELETED via Batch 3 | dead-state, zero writers post-W26 refactor |

| `static_method_stack_` (jit::Stack) | CLOSED via Batch 5 | rename to _cpp convention |

| `temps_` (TempAllocator) | CLOSED via Batch 6 | rename + 73-site mechanical sed |

§5 keep-bias is a DESIGN CHOICE (architectural decision, not deferral).

PhxArray-equivalent C-port for std::vector / unordered_map / Stack /

TempAllocator is multi-session-per-container scope; bridging at the

opaque-pointer surface is the tractable Phase 3 endpoint.

7 _cpp bridges shipped across B1–B6:

1. `hir_builder_state_init` (B1 ctor)

2. `hir_builder_state_parse_exception_table_c` (B1 algorithm)

3. `hir_builder_state_exception_table_push_cpp` (B1 write)

4. `hir_builder_state_exception_table_size_cpp` (B2 read)

5. `hir_builder_state_exception_table_entry_cpp` (B2 read)

6. `hir_builder_state_find_exception_handler_c` (B2 algorithm)

7. `hir_builder_state_block_map_blocks_lookup_cpp` (B4 read)

8. `hir_builder_state_static_method_stack_pop_cpp` (B5 read)

9. `hir_builder_state_temps_alloc_stack_cpp` (B6 alloc)

PhxHirBuilderState struct: 5 Class A members (code, preloader,

current_func, func, kwnames). Class B members not in struct (kept C++

behind opaque-access via the 7 _cpp bridges).

- **W44 caller-gate** (pre-Phase 3): DO-NOT-USE marker enforcement.

- **W45 §1–§2 bridge-sig falsifier** (pre-Phase 3): signature mutation +

build-fail verifier. 15/15 fixtures cover Phase 1 #2–#7 + Phase 3

Batches 1, 2, 4, 5, 6 bridges.

- **W45 §3.5 derivation-drift falsifier** (mid-Phase 3, bfc6321b77):

4 fixtures (BEFORE_ASYNC_WITH + _Py_ID + ExceptionTableEntry.depth +

block_map_blocks_lookup_cpp return-type). Integrated as

gate_phoenix.sh Step 1g (eb3cdf3f54), BUILD MODE per push for

builder*.{cpp,h,c} touch.

- **§3.5 5/5 backstop:** triggered post-Batch 4 land per

supervisor 23:49:22Z; impl shipped same workstream.

4-criterion floor enforced per commit:

1. geo-mean ≥ 1.0x

2. geo-mean drop ≤ 5% same-session

3. no single bench drops > 20% same-session

4. no single bench < 0.5x absolute

Phase 3 series: 1.27x → 1.29x → 1.28x → 1.26x → 1.29x → 1.26x. Net

geo-mean change ≈ -1% across 6 batches; well within noise floor;

zero floor violations.

Per `docs/tier8-class-b-cport-migrate-arm-spec.md` (theologian

01:01:50Z, supervisor 01:02:46Z ADOPTED):

- Pilot field: `exception_table_` (POD-equivalent per Phase 3 §2.2;

4 bridges → 0 on full port to PhxArray).

- Acceptance criterion #10: pilot must net-subtract ≥ +257L of Phase 3

foundation cost (validates "transitional cost paid back" framing

vs "permanent scaffold").

- Estimated pilot subtraction: ~-150L (4 bridge impls + 4 decls +

C++ struct/field/shims). Brings Phase 3 + Tier 8 cumulative from

+257L to ~+107L.

- Full Tier 8 across all 4 Class B containers projects net-negative

vs Phase 3 foundation.

- Phase 3 spec: `docs/tier7-phase3-hirbuilder-state-extraction-spec.md`

(theologian 22:59:11Z, supervisor 22:59:54Z + 23:00:15Z amendments)

- §5 amendment: pending theologian post-this-summary edit ("keep-bias

as design choice + Tier 8 migrate-arm pilot scheduled" — replaces

withdrawn "FINAL" framing per pythia #103)

- Tier 8 spec: `docs/tier8-class-b-cport-migrate-arm-spec.md`

(theologian 01:01:50Z, supervisor 01:02:46Z ADOPTED)

- W44: `scripts/check_do_not_use_callers.sh`,

`docs/w44-do-not-use-callers-gate.md`

- W45: `scripts/w45_bridge_drift_falsifier.sh`,

`scripts/w45_section_3_5_derivation_drift.sh`,

`docs/w45-bridge-signature-drift-falsifier.md` (§§1–2 + §2.5/§2.7)

- Pythia checkpoints: #89 (Phase 3 spec gate), #90/#91 (W45 trigger),

#92 (cross-post storm), #93 (block_map writer-grep + per-bench

floor + §3.5 trigger amendments), #94 (per-bench mechanized untested

+ §5 keep-bias risk), #103 (cathedral-scaffold six-month-regret +

Tier 8 migrate-arm pilot demand)

- MEMORY.md terminal goal: ZERO C++ — Phase 3 is foundation toward,

not satisfaction of