Engineering Principles

Twenty-four principles distilled for OMC's lanes from the pstack principle library (credited above) and rewritten against OMC's own mechanisms. Each names when it applies and which lane carries it. This is a discipline skill: it shapes how work is done; it never gates delivery on its own.

When to use

• a fix has failed twice, or two fixes share one explanation
• debugging, verification, or benchmarking work is starting
• a design choice repeats a shape assumption across files
• delegation prompts are being written and a lane's standing principles should travel with the brief

When not to use

• a one-line mechanical edit with an obvious check
• a hotfix under time pressure — state which principle you skipped and why in one line, then proceed

Core

Laziness Protocol

Refactoring, sizing a diff, or tempted to add abstractions, layers, or signal threading. Bias to deletion and the smallest change that solves the problem. Composes with minimal-code-discipline. Carried by executor and code-simplifier.

Foundational Thinking

Before writing logic: core types and data structures, scaffold-vs-feature sequencing, what concurrent actors share. Carried by architect and planner.

Redesign from First Principles

Integrating a new requirement into an existing design. Redesign as if the requirement had been foundational from day one, instead of patching the old shape around it. Carried by architect.

Attack the premise

When two or more attempted fixes share one assumption and all failed the same gate, stop writing fix three. Write the shared assumption down, test it directly, and let the result choose the next move. Carried by critic during plan gap analysis and by debugger before a third retry.

Subtract before you add

Before sequencing an addition, refactor, or rewrite, remove the dead weight first and build on the simpler base. Carried by executor and code-simplifier.

Minimize reader load

Reviewing or shaping code that is hard to trace. Count layers and hidden state, collapse one-caller wrappers, shrink mutable scope. Carried by code-simplifier and writer.

Outcome-oriented execution

Planned rewrites and migrations with explicit phase boundaries. Converge on the target architecture; do not preserve throwaway compatibility states. Carried by planner.

Experience first

Product, UX, or feature-scope tradeoffs. Choose user delight over implementation convenience, and say the tradeoff out loud when you take it. Carried by designer.

Exhaust the design space

A novel interaction or architectural decision with no precedent. Build 2-3 competing options and compare before committing — the arena and architect skills are this principle operationalized. Carried by architect.

Build the lever

Any non-trivial repeated work. Build the tool that does or proves it — codemod, script, generator — rather than doing it by hand a third time; the tool is the artifact a reviewer reruns. Carried by executor.

Architecture

Model the domain

When stateful logic branches a lot or repeats a shape assumption across files, encode the domain in a structure — a state machine, a typed model, a registry, a reducer — instead of scattering conditionals. OMC's graph runtime (graph skill) is this principle at full size. Carried by architect.

Boundary discipline

Wiring validation, error handling, or framework adapters. Guards at system boundaries, trust internal types, keep business logic pure. Carried by architect and executor.

Type system discipline

Designing types or signatures in any typed language. Make illegal states unrepresentable, brand primitives, parse external data at boundaries; in TypeScript, typescript-best-practices grounds this in syntax. Carried by architect and executor.

Make operations idempotent

Design commands, lifecycle steps, and loops that run amid crashes and retries to converge to the same end state. OMC's team recovery replays worker checkpoints idempotently; user code deserves the same property. Carried by executor.

Migrate callers, then delete legacy APIs

Introducing a new internal API while old callers exist. Migrate every caller and delete the old surface in one wave; a compatibility shim with no expiry is a second system. Carried by executor.

Separate before serializing shared state

Concurrent actors might write the same file, branch, key, or object. Eliminate the sharing first (a writer per worktree is OMC's house form); locking is the fallback, not the first move. Carried by executor and team.

Verification

Prove it works

Done means verified against the real artifact — the command's actual output, the passing test, the rendered page — never a proxy and never "it compiles". The verify skill owns the evidence format. Carried by verifier.

Fix root causes

Trace each symptom to the first place the system went wrong and fix it there. A guard for a state that should not exist is a workaround, not a fix; it is legitimate only when that state itself is legitimate. Carried by debugger; verifier treats symptom-level patches as incomplete work.

Sequence work into verifiable units

Multi-step work — sweeps, migrations, runs of similar edits — and how commits and PRs stack. Small units that each end in a check, verified before the next, ordered so the sequence proves itself. Carried by planner and git-master.

Test behavior, not implementation

Assert what users of the code can observe. A test worth keeping fails when the behavior breaks and passes when only internals change. Carried by test-engineer.

Explain the number

Before trusting, reporting, or acting on a measured number, find what limits it and rule out that it measured something other than the work you think. Label every claim measured, inferred, or guess in the same sentence. The benchmark-checklist skill owns the full procedure. Carried by scientist and by any lane reporting performance.

Delegation

Guard the context window

Route bulk reading and large outputs to subagents; keep summaries in the lead thread. Context spent on a wall of log output is context not spent on judgment. Applies to every lane and to the orchestrator itself.

Never block on the human

Tempted to ask "should I do X?" on reversible work. Proceed, present the result, let the human course-correct; reserve questions for genuine product calls no experiment can settle. Carried by every lane.

Meta

Encode lessons in structure

The second time you write the same instruction, stop writing it a third time: encode it as a lint rule, a runtime check, a script, or — in OMC — a learned skill via skillify, or an enforcement via correct. Text rots; structure reruns. Carried by skillify and self-improve.

Distribution map

When delegating, prepend the delegate lane's standing principles to the brief.

Reporting

When this skill is active, name in the reply which principle shaped each non-obvious decision, in one clause. When a principle and an explicit user instruction conflict, the user wins; say so in one sentence.