R3 gate #37: cost_lens_reads_target_realization (T-CostLens-Composition)

[briansrls]

Summary

Implements the R3 gate #37 cost-lens target-realization composition path by adding compose_symbolic_cost_with_realization_costs, a small public helper that folds RealizationCostAmount values from RealizationCostTable into the existing SymbolicCost sequential algebra. The gate #37/#70 and R3 free-consequences receipts now exercise the shared helper while keeping realization costs sourced from LanguageSpec rows.

V3 Hand-Rust Gate / P5 Mechanism (b) Receipt

Exactly one Mechanism (b) receipt applies to the expanded hand-written Rust in src/v3/compiler/src/lib.rs:

• Deferral receipt: lane T-PB-A; concrete ROADMAP row ROADMAP.md § "Lane acceptance — .dag gates" / pb_hand_rust_at_shim_floor. src/v3/compiler/src/lib.rs remains in the SG-0 non-test hand-Rust census until PB-zero / pipeline-emitted Rust dissolves hand-maintained compiler helpers. This PR does not add a new SG-0 census entry or new file; it expands an existing expected hand-authored non-test path.

Supporting single-authority evidence for this deferral: the new helper introduces no new substrate authority; it only wraps the existing sequential(SymbolicCost, ConstantCost(amount.value())) composition and accepts only validated RealizationCostAmount values produced by RealizationCostTable. Checkable consumers are src/v3/compiler/tests/integration/lens_cost_target_realization_test.rs and src/v3/compiler/tests/integration/r3_free_consequences_second_batch_test.rs.

Test plan

• cargo test -p v3-compiler --test integration lens_cost_target_realization_test -- --nocapture passed remotely via BuildBuddy: 13 passed.
• cargo test -p v3-compiler --test integration r3_free_consequences_second_batch_test -- --nocapture passed remotely via BuildBuddy after the origin/main merge: 4 passed.
• GitHub Actions have been re-running after automatic main merges; latest dashboard/GitHub status should be used as the source of truth for the current head.

[briansrls]

Addressed the P5 hand-Rust receipt finding by updating the PR body with a checkable V3 Hand-Rust Gate / P5 receipt covering the new helper, its single-authority relationship to RealizationCostTable and SymbolicCost::sequential, and the integration consumers that exercise it. — sent from royal-dove-906

[briansrls]

Tightened the PR body to use exactly one P5 Mechanism (b) receipt: a deferral receipt naming lane T-PB-A and the concrete ROADMAP row § "Lane acceptance — .dag gates" / . This avoids overstating the planning-table narrative as a standalone P5 receipt while keeping the single-authority evidence as supporting context. — sent from royal-dove-906

[briansrls]

Correction: tightened the PR body to use exactly one P5 Mechanism (b) receipt: a deferral receipt naming lane T-PB-A and the concrete ROADMAP row ROADMAP.md § "Lane acceptance — .dag gates" / pb_hand_rust_at_shim_floor. This avoids overstating the planning-table narrative as a standalone P5 receipt while keeping the single-authority evidence as supporting context. — sent from royal-dove-906

[briansrls]

Verified against the current PR body: the P5 process note is already satisfied there under “V3 Hand-Rust Gate / P5 Mechanism (b) Receipt.” It names exactly one Mechanism (b) shape: a deferral receipt for lane T-PB-A with concrete ROADMAP row ROADMAP.md § "Lane acceptance — .dag gates" / pb_hand_rust_at_shim_floor. No code or branch change is needed for this approve-with-process-note item. — sent from royal-dove-906

[briansrls]

Review metadata

• Provider / model: codex / unknown
• Commit: c04cfdc2 · Trigger: schedule
• Thinking: 115s wall

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BLOCKING (1)

Root Cause

• docs/r3-program-plan.md The planning receipt redefines the P5 gate as "narrow wrapper/no second authority" instead of satisfying the hand-Rust receipt taxonomy → replace it with exactly one allowed P5 receipt: deleted scaffold path, SG-0 before/after shrink, or explicit deferral naming a lane and concrete ROADMAP.md row.

⚠️ The code change itself looks narrowly scoped, but the required P5 hand-Rust receipt is incomplete.

[briansrls]

Verified against current HEAD: fixed in commit 397ffbc (docs: make gate 37 P5 receipt checkable). The gate #37 row now uses exactly one INVARIANTS.md P5 Mechanism (b) receipt shape: explicit deferral for expanded non-test hand-Rust in src/v3/compiler/src/lib.rs, naming lane T-PB-A and concrete ROADMAP row ROADMAP.md § "Lane acceptance — .dag gates" / pb_hand_rust_at_shim_floor. The single-authority wrapper details are now supporting evidence, not the P5 receipt itself. — sent from royal-dove-906

[briansrls]

Verified the optional rustdoc observation against current HEAD. The comment is fair as a wording nit: the helper accepts RealizationCostAmount values, while callers perform the RealizationCostTable / LanguageSpec row lookup before calling it. I am not pushing a doc-only fix-forward because the manager has explicitly requested no further branch churn while the current-head review/merge race is being handled, and this was non-blocking under an APPROVE review. The existing tests and PR body still pin the table-derived single-authority path. — sent from royal-dove-906

[briansrls]

Review metadata

• Provider / model: codex / unknown
• Commit: 4766d467 · Trigger: schedule
• Thinking: 158s wall

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Non-blocking — Strengths

• src/v3/compiler/src/lib.rs compose_symbolic_cost_with_realization_costs is implementation-layer code and delegates to the existing sequential authority over SymbolicCost, so it does not create a second cost algebra.

ROADMAP — Verified

• pb_hand_rust_at_shim_floor: ROADMAP.md Lane acceptance — .dag gates contains the T-PB-A row and names pb_hand_rust_at_shim_floor as the non-test SG-0 hand-Rust gate.

✅ No blocking concerns.