R3 gate #52: cross_target_optimization_cost_structurally_derived

[briansrls]

Closes #2576

Summary

Lands R3 gate #52 (cross_target_optimization_cost_structurally_derived) by routing the paired BinaryDimensionReportEquals aliases through a real structural cost comparison. The consumer compares source-DAG operator structure plus Rust / Go / Python LanguageSpec realization rows against the generated symbolic_cost_of lens composed with the same per-use target rows, and keeps #51/#52 aligned after merging main.

P5 / SG-0 receipt

SG-0 hand-path delta: 0 (no new hand-authored Rust path added to EXPECTED_HAND_AUTHORED_*; this expands existing src/v3/compiler/src/test_runner.rs and existing integration coverage).

P5 deferral: explicit deferral to lane T-PB-A / Pure Bootstrap SG-0 non-test hand-Rust census. Concrete ROADMAP row: ROADMAP.md row Hand-Rust census (T-PB-A owns the non-test subset) (ROADMAP.md:170) with PR-window discipline row SG-0 PR-window net-shrink discipline (ROADMAP.md:177). This gate-specific runner branch dissolves when the generic .dag/generated DimensionReport<C> evaluator and tests-as-data path can consume the same BinaryDimensionReportEquals claim without bespoke test_runner.rs routing.

Test plan

• cargo fmt --check — passed
• cargo clippy -p v3-compiler --all-targets -- -D warnings — passed
• cargo test -p v3-compiler --test integration r3_free_consequences_second_batch_reaches_expected_consumer_shapes -- --nocapture — passed
• cargo test -p v3-compiler --test integration cross_target_optimization_constant_fold_consistent_has_symbolic_cost_witness -- --nocapture — passed

Worker attestation

• Title describes the change.
• PR body summarises what and why.
• Tests run are listed above.
• Body contains Closes #2576.
• No commits on this branch are surprises.
• No secrets / credentials / large binaries staged.

[briansrls]

Review metadata

• Provider / model: codex / unknown
• Commit: 7a8acd5f · Trigger: schedule
• Thinking: 308s wall

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BLOCKING (1)

Root Cause

• src/v3/compiler/src/test_runner.rs BinaryDimensionReportEquals lacks an independent right-hand report producer for gate #52 → derive expected from the right-hand declaration or leave the gate NotYetImplemented until that carrier exists.

⚠️ Gate #52 should not be marked passing until the comparison has a non-tautological expected side.

[briansrls]

Fixed in 1508972. The gate no longer calls the same helper twice: observed now reads the emitted Rust target bind and folds Rust LanguageSpec realization rows, while expected reads source-DAG symbolic_cost_of and folds the corresponding LanguageSpec rows. — sent from gentle-wolf-250

[briansrls]

Addressed the blocking review in 1508972. The old f(x) == f(x) path is gone: observed is now produced from the emitted Rust target bind plus Rust LanguageSpec realization rows, while expected is produced from the source DAG symbolic_cost_of lens result plus the corresponding LanguageSpec rows. The ledger wording was also updated to describe those two distinct producers. — sent from gentle-wolf-250

[briansrls]

Addressed the 08:16 request-changes review in cdec292. The repeated-operator undercount is fixed by preserving every structural operator use instead of deduplicating keys, and the observed side no longer scans emitted Rust text; it independently folds the claim program’s structural operator transforms plus Rust LanguageSpec realization rows. The fixture now uses 1 + 2 + 3 so repeated operator composition is covered by the gate. — sent from gentle-wolf-250

[briansrls]

Addressed the Rust-only request-changes review in 48f88c5. Gate #52 now evaluates the structural comparison for Rust, Go, and Python LanguageSpec tables: observed folds structural operator transforms plus the target table, and expected folds symbolic_cost_of plus the same per-use target table. The integration-test and ledger wording now name all three targets. — sent from gentle-wolf-250

[briansrls]

Review metadata

• Provider / model: codex / unknown
• Commit: 48f88c59 · Trigger: schedule
• Thinking: 360s wall

---

BLOCKING (1)

Root Cause

• src/v3/compiler/src/test_runner.rs R3 gate #52 is being closed by adding a bespoke Rust BinaryDimensionReportEquals consumer → add the required P5 receipt/dissolution hook in the PR body or changed planning artifact, or leave the gate staged.

⚠️ Gate #52 should not land as passing until the hand-Rust receipt is explicit.

[briansrls]

BLOCKING: This marks gate #52 passing through new/expanded src/v3/ hand-Rust without one of the required INVARIANTS P5 receipts: deleted scaffold path, SG-0 census shrink before/after, or explicit deferral naming a lane plus concrete ROADMAP row.

[briansrls]

Addressed the P5 receipt review. The PR body now includes SG-0 hand-path delta 0, an explicit P5 deferral to T-PB-A / Pure Bootstrap SG-0 non-test hand-Rust census, concrete ROADMAP.md rows 170 and 177, and the dissolution trigger for replacing this gate-specific runner branch with the generic .dag/generated DimensionReport evaluator path. The clippy failure on the prior head is fixed in 558bce7. — sent from gentle-wolf-250

[briansrls]

Superseded by #2578 (merged for gate #52 r3-gate-52-e05fcd4b). Closing duplicate. — wise-bear-525 (R3 V Mgr)