Structural Refactoring

Structural Refactoring

Principle expression

Primary: P07 Supporting: P02, P13, P15

Scope

Own one judgment: how can the present code be reconstituted into a better structure while preserving the behavior and constraints that matter?

Treat a refactor as a semantic-preservation problem, not a file-moving task. Do not infer boundaries from file length, directory fashion, an AST graph, or the number of available agents. Do not use this skill to decide new product behavior or accept its own result.

Principle source

Use a host Sequence and matching interpretations when the host declares them. Otherwise use this skill's read-only fallback in references/sequence.md. Read only P07, P02, P13, and P15. A live task may select a different current lead, but it does not create co-primary doctrine.

Start

Ground the refactor before editing:

Actual target and observed behavior:
Structural pressure or requested change:
Preservation contract:
Observed impact field:
Strongest no-refactor alternative:
Smallest candidate boundary:
Verification and acceptance owner:

If the requested change is a local cleanup whose impact is already visible, work under ordinary disciplined development. If the desired architecture or behavior is unsettled, route that decision before refactoring.

Core method

1. Recover the concrete whole. Read the target, its callers, tests, public contracts, accepted design, and recent relevant history. Run the current verification surface when practical. Separate observed facts from inferred responsibilities and preferences.

2. Classify the change. Confirm that the task changes code structure while intending to preserve named observable behavior. Route adjacent problems through the boundaries below rather than hiding them inside the refactor.

3. Build the smallest sufficient impact field. Trace only what can change the boundary or verification decision:

   • public entry points and direct consumers;
   • state, effects, lifecycle, error, persistence, and concurrency boundaries;
   • dependency direction and strongly coupled definitions;
   • invariants and high-risk paths;
   • tests, types, build checks, and runtime observations able to expose drift.

   Prefer compiler, language-server, AST, call-site, and repository evidence for exhaustive facts. Use model judgment for responsibility, cohesion, and trade-offs. Never let a generated summary silently replace the source field.

4. Compare boundaries. Preserve the strongest no-refactor case and compare the fewest alternatives needed to expose the real trade-off. Reject a split that only shortens files while increasing cross-boundary traffic, duplicated state, unstable interfaces, or migration risk. Select the smallest boundary that resolves the named structural pressure and preserves hard constraints.

5. Allocate attention proportionally. Default to one agent with the whole impact field. Use Work Cells, subagents, or parallel specialist views only when distinct ownership, effects, callers, or preservation risks are likely to be missed and can be reviewed independently. Give every view the same authoritative field, retain dissent, and treat synthesis as a proposal. Do not vote facts into existence or require a swarm for routine work.

6. Design reversible checkpoints. Order moves by real dependencies so every checkpoint can typecheck or run a focused verification. Keep behavior change, API redesign, formatting churn, and unrelated cleanup out of the refactor unless they are necessary to preserve the contract and are named explicitly.

7. Execute and observe one checkpoint at a time. Update definitions and consumers together, inspect the diff, and run the smallest check capable of exposing the predicted failure. Stop and revise the impact field when an observation contradicts the plan.

8. Settle through independent verification. Compare the final structure against the preservation contract, public surface, impact field, and accepted boundary. Record traceable checks and residual risk. A designated reviewer or human accepts a consequential refactor; the implementing agent does not turn its report into fact.

Boundaries and routing

Work Cell is an optional executor and evidence source, not this skill's owner or a required stage. AST and code-graph tools are optional observations, not a portable runtime dependency.

Verification

Read evaluation when designing a consequential refactor, evaluating this skill, or deciding whether parallel analysis is worth its cost. Retain only the probes that can change the implementation or acceptance decision.

Completion standard

A refactor is ready only when the structural pressure, preservation contract, impact field, selected boundary, executable checkpoints, traceable verification, and acceptance owner are explicit. Passing syntax or type checks proves only the properties they observe. If behavior equivalence, caller impact, or ownership remains uncertain, report the uncertainty and do not claim completion.