contract(class_view): execute_compute_dag — the ORDER half of the ActionDef value executor

[AdaWorldAPI]

What

Adds execute_compute_dag to lance-graph-contract::class_view — the ORDER half of the ActionDef value executor (the medcare transpile arc's lane-3a increment 1).

• ExecuteComputeError<E> — Cyclic (no topological order; the registry-build gate should have rejected the manifest) and Compute { target, source } (the consumer closure failed at a target; abort-at-target, earlier targets stay written).
• execute_compute_dag<S, E>(edges, store, compute_target) — refuses Cyclic before running any target (store untouched), else runs targets in compute_dag_topo_order so every precedent is recomputed before its dependents. Returns the executed order.

Split of responsibilities (commitment: thinking lives upstream, values live with the row owner)

This function owns sequencing only. The consumer's compute_target closure owns value semantics — it recomputes field position t on the consumer-owned store (e.g. a hand-ported score formula). Leaves are never passed to compute_target; they are the already-present inputs.

Why now

The medcare consumer's sono_compute_parity witness (MedCare-rs, follow-up PR) dispatches the medcare-core::sono Recal_* hand-port through this primitive and proves bit-parity over the two-layer f_2_7 DAG (6 joints → recal_ges). That is the gate the ActionDef-executor plan requires BEFORE draining any hand-ported module — and it needs this primitive on main so the consumer's vendored lance-graph-contract path resolves it.

Verification

• cargo test -p lance-graph-contract class_view — 41/41 passing (4 new: in-order chain, cycle-untouched, abort-at-target, empty-noop)
• Zero new dependencies (std only)
• Board hygiene: LATEST_STATE.md contract-inventory row updated in the same commit (per the Mandatory Board-Hygiene Rule)

🤖 Generated with Claude Code

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Generated by Claude Code

Summary by CodeRabbit

• New Features
  • Added dependency-aware recomputation for class values.
  • Recomputations now run in dependency order, with results available to subsequent calculations.
  • Cyclic dependencies are rejected without changing existing values.
  • Processing stops at the first failed calculation while preserving earlier results.
  • Empty recomputation plans complete without changes.

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: f68ef4d8-7796-4be3-9e2e-a22b49aab616

📥 Commits

Reviewing files that changed from the base of the PR and between d641a7d and c7903d5.

📒 Files selected for processing (2)

• .claude/board/LATEST_STATE.md
• crates/lance-graph-contract/src/class_view.rs

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📝 Walkthrough

Walkthrough

Adds a public recompute-DAG executor for class fields, including topological execution, cycle detection, target-specific errors, abort-on-failure behavior, and comprehensive unit tests.

Changes

Class recompute DAG execution

Layer / File(s)	Summary
Executor API and failure semantics crates/lance-graph-contract/src/class_view.rs, .claude/board/LATEST_STATE.md	Adds ExecuteComputeError and execute_compute_dag, documenting topological execution, cycle refusal, and immediate failure handling.
Executor behavior tests crates/lance-graph-contract/src/class_view.rs	Tests dependency ordering, value visibility, cycle safety, partial recomputation, and empty-DAG no-op behavior.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Caller
  participant execute_compute_dag
  participant Store
  Caller->>execute_compute_dag: Provide ComputeEdge entries and compute_target
  execute_compute_dag->>execute_compute_dag: Build topological recompute order
  execute_compute_dag->>Store: Recompute each target in order
  Store-->>execute_compute_dag: Return success or target failure
  execute_compute_dag-->>Caller: Return executed order or ExecuteComputeError

Loading

Poem

I’m a bunny with a DAG to run,
Topological hops beneath the sun.
Cycles stop before writes begin,
Failed fields halt the race within.
Empty paths nap; tests cheer—
Clean recomputes bloom this year!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly names the new execute_compute_dag change in class_view and matches the PR’s main objective.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

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