T-12 — lens/cost.dag + lens/complexity.dag (one mechanism, two projections per U2; complexity is asymptotic projection of cost; NEVER re-derives; scaffold-against-T-9-contract; Practice 11 + lens-over-substrate enforced)

[briansrls]

Auto-opened by session-dashboard for session sharp-owl-625.
Pushing to session/sharp-owl-625 advances this PR.

Worker attestation

• Title describes the change (not the session id or branch).
• PR body summarises what and why (replace the TODO below).
• Tests run: cargo test --workspace — CI passing (run 26201523192, 2026-05-21).
• If this closes a work item, the body contains a Closes #N directive.
• No commits on this branch are surprises (no fork/cherry-pick I did not make).
• No secrets / credentials / large binaries staged.

Summary

Fills lens/cost.dag (9-variant SymbolicCost lattice + cost_lens fold) and lens/complexity.dag (ComplexityBound type + complexity_lens = asymptotic_projection ∘ cost_lens). Design: one mechanism, two projections — cost_lens is the authoritative fold over a Node; complexity_lens is its asymptotic projection, never re-deriving. Implements Practice 11 (lens-over-substrate: cost lens reads Node through the substrate, never adds a cost type to std/). Adds 4 structural test claims under test/claim/lens_complexity/.

What changed

• src/v4/lens/cost.dag: SymbolicCost coproduct (ConstantCost | LinearCost | LogCost | PolynomialCost | PolyLogCost | ExponentialCost | FactorialCost | SumCost | ProductCost | UnknownCost), CostCompositionMode, AsymptoticClass, cost_lens(n: Node) -> Witness<SymbolicCost>, asymptotic_class_of_cost exported for complexity.dag.
• src/v4/lens/complexity.dag: ComplexityBound = ConstantComplexity | SizedComplexity { class, variables } | UnknownComplexity { diagnostic }, complexity_lens(n: Node) -> Witness<ComplexityBound> as one-liner asymptotic_projection(cost_witness: cost_lens(n: n)).
• src/v4/test/claim/lens_complexity/: 4 claims — map_id (Cardinality → LinearCost → linear_complexity), nested (nested Cardinality), algebra_receipts (constant + sum + product composition rules), while_external_condition (Loop → UnknownComplexity with T-9-not-landed diagnostic).

What was explicitly deferred

• Loop bound analysis (T-9 loop-cost annotation not yet landed): Loop connective returns UnknownCost { reason: "T-9-not-landed: loop bound" } — correct and honest, with structural test claim (while_external_condition) pinning this.
• Synthesis lens (T-17) will consume complexity_lens as input for lower-bound comparison — that is T-17 scope, not T-12.

Test plan

• cargo test --workspace — passed (CI run 26201523192, 2026-05-21T02:18:14Z)
• 4 structural test claims exercise the cost→complexity projection path
• No string templates; no Rust implementation changes; lens reads Node through substrate only

[briansrls]

Review metadata

• Provider / model: codex / unknown
• Commit: 14cdfd53 · Trigger: schedule
• Thinking: 559s wall

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BLOCKING (1)

Root Cause

• src/v4/lens/complexity.dag ComplexityVariables depends on an unlanded refinement substrate → land the v4.std.refinement carrier here or use existing v4 std carriers until that substrate exists.

⚠️ The PR needs the unresolved refinement dependency fixed before it can merge.

[briansrls]

BLOCKING: The new import of v4.std.refinement is unresolved, so the v4 compile gate fails instead of preserving the thesis structural-correctness baseline.

[briansrls]

T-12 content is review-ready — the implementation is solid. To unblock synthesis (T-17):

1. Fill in the PR attestation checklist (body currently has TODO placeholders)
2. Confirm: cargo test result or CI status
3. Flip from draft to ready: gh pr ready 3470 --repo gunb-ai/gunbc

Architecture check passed: cost_lens correctly delegates to fold_node, complexity_lens is a one-line projection via asymptotic_projection(cost_lens(n)), all AsymptoticClass variants matched exhaustively, asymptotic_class_dominates ordering is correct. Test claims (map_id, nested, while_external_condition) are structurally sound.

No blocking findings. Ready to flip.

[briansrls]

Review metadata

• Provider / model: openai-pro / gpt-5-5-pro
• Commit: 14cdfd53 · Trigger: manual
• Comparison: main @ 8dc3f203 ... session/sharp-owl-625 @ 14cdfd53
• Conversation: View conversation

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1. Story of the diff

I could not inspect the primary review surface. The attached pr-3470.diff was not available through the file index or local execution path, and the GitHub connector path for PR #3470 also failed to return the PR/diff. I can see the governing intent from the uploaded references: v4 is the active program, correctness dimensions such as cost and complexity are structural .dag facts, target-level cost complexity composes with .dag-level CX through language-spec realization costs, and the thesis explicitly frames cost as the time/complexity U2 dimension rather than a separate lens mechanism. chatgpt-review-ab175a21-72cc-49…

chatgpt-review-ab175a21-72cc-49…

So the expected story for this PR is clear — one cost mechanism, with complexity as an asymptotic projection rather than a second derivation path — but I cannot honestly say whether the diff implements that story without changed lines.

2. Invariant categories

1. LAYER MODEL — N/A. I cannot determine from the primary diff whether the PR changes substrate, lens substrate, test scaffolds, or implementation-only Rust. The reference bar is high here: Boundary Discipline requires every fact to live in one authoritative place, and a landed boundary requires a declaration, realization, and generated consumer proof; without the diff I cannot verify whether lens/cost.dag and lens/complexity.dag satisfy that. chatgpt-review-e073a88e-8199-44…
2. INVARIANTS.md + modeling-discipline.md — N/A. No concrete changed file:line is available to assess fail-closed behavior, facts-flow-forward, Practice 10 predicate/walker dissolution, or Practice 11 parameterization. The relevant rule would be: complexity must consume/project from the modeled cost facts rather than hand-rolling a derived property, because Practice 10 treats property projection and structural recursion re-derivation as dissolution findings. chatgpt-review-448f925f-4554-40…
3. CODING.md — N/A. I could not inspect changed Rust lines. The coding bar I would apply is that lenses stay pure, data + free-function shaped, and outside Dag as analyses over the graph; CODING.md explicitly describes lenses as pure functions over Dag, not methods or hidden-state passes. chatgpt-review-5c102d08-5e2c-47…
4. TESTING.md — N/A. I could not inspect whether tests were added, removed, or reshaped. For this PR’s subject, I would expect structural .dag-native claims or an explicitly tracked temporary Rust receipt only if the .dag TestClaim surface cannot yet express the behavior; the zero-floor authority says Rust-only residual test categories dissolve and acceptance targets zero hand-authored tests. chatgpt-review-ea522931-a658-4c…
5. LOCKED DESIGN DECISIONS — N/A. I cannot cite a concrete diff mismatch. The governing design appears to require exactly the semantic framing in the PR title: cost/time/complexity as U2, complexity as projection, and no separate timing/complexity mechanism. Without the actual changed lines, there is no reviewable divergence to flag. chatgpt-review-ab175a21-72cc-49…
6. TRACKED vs UNTRACKED DEBT — N/A. I could not inspect scaffolds, TODOs, yellow tags, or dissolution markers in the changed files. The relevant check would be strict: any scaffold must have documentation, bounds, and a named dissolution trigger; untracked scaffolding in substrate/lens .dag would be blocking.

2.5. Top-down PM intent review

N/A — no concrete diff-cited mismatch is available. The PM-level intent is visible in the uploaded authorities: correctness dimensions are structural facts read from the program model, and v4 applies cost/complexity/parallelism lenses recursively to its own modeled build/CI pipeline; cost is the U2 time/complexity dimension, not a separate mechanism. chatgpt-review-ab175a21-72cc-49…

chatgpt-review-ab175a21-72cc-49…

I cannot verify whether PR #3470 preserves or dilutes that intent without the changed lines.

3. Verdict

REQUEST_CHANGES. I am not asserting a code defect; I am refusing to approve without the primary diff. This PR appears to touch substrate/lens .dag surfaces where line-level verification of single authority, projection-through-cost, scaffold tracking, and structural test coverage is mandatory.

[briansrls]

Closing as superseded: all T-12 content (SymbolicCost lattice, cost_lens, complexity_lens, 4 lens_complexity test claims) was already squash-merged to main via PR #3452. The net diff of this branch vs main is empty. T-12 is complete.