OpenChamber Change Discipline

Core Principle

Make the smallest complete change and validate at the narrowest level that covers the real risk.

Before Editing

1. Inspect nearby implementation, callers, and tests before introducing a pattern.
2. Classify every applicable change risk below.
3. Identify every affected consumer, runtime, persisted format, and public export. This step is complete only when each risk has an owner and required validation.

Risk Classification

Apply every matching category. Do not escalate local work into workspace-wide ritual, and do not treat a type-only export as local merely because it emits no JavaScript.

Structural Discipline

• Preserve behavior established by callers and tests unless the request replaces it. Keep the diff scoped to the complete requested behavior.
• Make the normal use-case path read top to bottom in domain terms. Keep orchestration entrypoints thin and move mechanics or domain logic behind focused, intention-revealing boundaries.
• Pull complexity downward only when a boundary hides meaningful mechanics, owns an invariant, isolates a proven integration, or captures stable repetition. Do not spread obvious code across pass-through layers.
• Prefer explicit dependencies and dependency injection over hidden module coupling.
• Follow local TypeScript types; avoid any, blind casts, and guessed payload shapes.
• Reject invalid inputs and broken preconditions early so the valid path stays flat. Do not force a numeric happy-path/error-path ratio when correctness requires substantial failure handling.
• Require evidence before adding retries, caches, compatibility paths, lifecycle machinery, or generalized race handling. Security, data-loss, destructive-operation, and concurrency invariants still require proactive design when the risk is inherent to the operation.
• Make partial failure, rollback, cleanup, and user-visible outcomes explicit for destructive or multi-step work.

Review Prompts

Before broadening a change, ask:

• Is the new abstraction reused or merely possible to reuse?
• What concrete complexity, invariant, stable repetition, or boundary does each new helper, interface, layer, and file pay for?
• Is the code in the package that owns the behavior?
• Does the change alter shared UI contracts across web, desktop, VS Code, or mobile?
• Does it change persisted data, IDs, routes, exports, generated files, or package entrypoints?
• Can failure leave optimistic state, caches, files, or remote state stranded?

For partial or destructive flows, answer explicitly:

• What remains valid after the first failure?
• What is rolled back or cleaned up?
• What can be retried or resumed safely?
• What does the user observe?

For persisted data, require a migration only when existing stored data needs conversion. Test downgrade compatibility only when older application versions are a concrete supported consumer. "Rollback" means preserving/restoring valid state after a failed write or migration unless a broader contract explicitly says otherwise.

Do not hide a required architectural migration behind a local heuristic. Do not turn a local fix into a speculative rewrite.

Validation Matrix

bun run check:changed is the pre-commit gate: run it once, right before a commit, on the finished diff. While iterating, run only the focused tests for the behavior you just changed; an edit to docs, comments, or strings needs no check at all.

When several agents edit one checkout in parallel, they edit and run single test files only. The coordinator runs type-check, lint, builds and full suites once, serially, on the combined diff: each tsc -b over packages/ui takes gigabytes, parallel copies have frozen the machine, and a check run mid-edit reports the other agents' half-finished work.

Use a sufficiently long timeout for broad checks. Report exactly what ran and what did not.

Choose affected builds/tests by tracing real consumers and runtime boundaries, not by running everything reflexively.

For type-only shared contracts, validate compile-time consumers. Add runtime serialization tests when the contract crosses a process, persistence, network, or untyped JavaScript boundary.

Test Design

• Prefer observable contracts, state transitions, failure handling, rollback, and operation counts.
• Test private helpers through public/module behavior when that captures the risk clearly.
• Assert internal map shape, helper calls, or call order only when that structure/order is itself a contract.
• Keep refactor tests resilient to equivalent internal implementations.
• For behavior-preserving refactors, establish the current behavior before changing structure.

Module Documentation

A module's DOCUMENTATION.md lives in its folder and holds what the code cannot show the next agent: what the module owns, what must stay true, and why it is built this way. A module gets its own document when it owns a contract other code relies on, an invariant, or a non-obvious design choice; a folder without any of these is covered by its parent's document.

The document has three parts:

• Ownership. What the module owns and where its boundary is: what belongs here and which neighbouring module owns the rest.
• Invariants. What must stay true, each stated so a change can be checked against it.
• Decisions. One ### Why X and not Y entry per non-obvious choice: the chosen approach, the alternative it was weighed against or replaced, and the reason in one or two sentences. A choice is non-obvious when a later reader could reasonably "fix" it back: a simpler design that was rejected, a deliberate workaround, a measured trade-off.

The document describes the module as it is now. When a decision changes, rewrite its entry around the new choice and keep the old approach as the rejected alternative, so the file stays current and carries no history to unwind. Spend its lines on reasons and contracts; file listings and function-by-function walkthroughs restate the code and go stale first.

Completion Standard

• Implement the behavior end to end, including rollback and cleanup.
• Run focused regression tests for the changed contract; when no test can cover it, say so in the report.
• Preserve unrelated changes encountered in shared files.
• The owning DOCUMENTATION.md is true of the new code and has a decision entry for every non-obvious choice the change made; a new module that meets the bar in Module Documentation has its own document.
• Perform a final simplification pass over your own diff, hardest after a rework or a removal: every branch, condition, prop, parameter, export, key, and helper the change made unreachable, always-true, or single-valued is gone, along with speculative branches, shallow wrappers, stale compatibility, and names that do not clarify intent.
• Before a commit, the pre-commit gate passes.