91  The Fifty World-Running Words

The 50 major words are the first vocabulary surface to review. Each has a term-specific shadow.

Sigil	Term	Cluster	Semantic	Gloss	Reviewed Shadow	Example
0001	0001 abstraction	Boundaries, seams, and collaboration	reviewed	A deliberate forgetting of detail so larger structure can be reasoned about without drowning in mechanism. Shadow: hiding the only failure that matters.	hiding the only failure that matters.	Before editing, state the abstraction obligation, the evidence that satisfies it, and the failure mode if it is missing.
0002	0002 adapter	Boundaries, seams, and collaboration	reviewed	A negotiated translator between unlike shapes. Use it when two systems must meet without infecting one another. Shadow: adapter jungles that preserve confusion rather than resolve it.	adapter jungles that preserve confusion rather than resolve it.	Before editing, state the adapter obligation, the evidence that satisfies it, and the failure mode if it is missing.
0006	0006 API gateway	Boundaries, seams, and collaboration	reviewed	A threshold that centralizes entry, policy, and routing at the edge of a service world. Shadow: a convenience chokepoint that quietly becomes a monolith.	a convenience chokepoint that quietly becomes a monolith.	Before editing, state the API gateway obligation, the evidence that satisfies it, and the failure mode if it is missing.
0012	0012 boundary	Boundaries, seams, and collaboration	reviewed	The line that says where one responsibility ends and another begins. Shadow: porous edges that smear blame, ownership, and test scope.	porous edges that smear blame, ownership, and test scope.	Before editing, state the boundary obligation, the evidence that satisfies it, and the failure mode if it is missing.
0013	0013 bounded context	Boundaries, seams, and collaboration	reviewed	A protection against semantic bleed: the same word may not mean the same thing in every subsystem. Shadow: false unification through shared names.	false unification through shared names.	Before editing, state the bounded context obligation, the evidence that satisfies it, and the failure mode if it is missing.
0030	0030 coupling	Boundaries, seams, and collaboration	reviewed	The hidden tax paid when change in one place forces change elsewhere. Name it early if you want modularity to survive contact with reality.	when a change in one component quietly forces coordinated edits across unrelated surfaces.	Before editing, state the coupling obligation, the evidence that satisfies it, and the failure mode if it is missing.
0034	0034 dependency inversion	Boundaries, seams, and collaboration	reviewed	Stable policy should not kneel before unstable detail. Shadow: concrete dependencies hard-wired into places that should remain portable.	concrete dependencies hard-wired into places that should remain portable.	Before editing, state the dependency inversion obligation, the evidence that satisfies it, and the failure mode if it is missing.
0055	0055 interface {Arch}	Boundaries, seams, and collaboration	reviewed	A disciplined seam that lets unlike bodies cooperate without swapping internal organs. Shadow: tight coupling and type bleed.	tight coupling and type bleed.	Before editing, state the interface obligation, the evidence that satisfies it, and the failure mode if it is missing.
0347	0347 schema {Data}	Boundaries, seams, and collaboration	reviewed	The declared shape of stored meaning. Shadow: drift, silent coercion, and backward-incompatible surprise.	drift, silent coercion, and backward-incompatible surprise.	Before editing, state the schema obligation, the evidence that satisfies it, and the failure mode if it is missing.
0576	0576 retry {Ctrl}	Runtime pressure, behavior, and operational physics	reviewed	Failure does not necessarily end the ritual; policy may permit another attempt. Shadow: blind repetition against a broken precondition.	blind repetition against a broken precondition.	Before editing, state the retry obligation, the evidence that satisfies it, and the failure mode if it is missing.
0598	0598 timeout {Ctrl}	Runtime pressure, behavior, and operational physics	reviewed	Waiting is not free and patience must have a boundary. A timeout is a contract with reality about how long uncertainty is allowed to persist.	when a timeout hides whether the operation failed, succeeded late, or is still running.	Before editing, state the timeout obligation, the evidence that satisfies it, and the failure mode if it is missing.
0615	0615 cache {Run}	Runtime pressure, behavior, and operational physics	reviewed	Keep likely things close so future cost falls. Shadow: stale truth delivered at machine speed.	stale truth delivered at machine speed.	Before editing, state the cache obligation, the evidence that satisfies it, and the failure mode if it is missing.
0684	0684 zero-copy {Run}	Runtime pressure, behavior, and operational physics	reviewed	Data movement stripped down to the minimum number of duplications. Use it when the bottleneck is physical movement rather than arithmetic.	when avoiding copies transfers lifetime and mutation hazards to the caller.	Before editing, state the zero-copy obligation, the evidence that satisfies it, and the failure mode if it is missing.
0778	0778 backpressure	Runtime pressure, behavior, and operational physics	reviewed	Resistance pushed upstream when demand outruns capacity. Without it, overload spreads faster than truth.	when pressure signals arrive too late and overload has already crossed the boundary.	Before editing, state the backpressure obligation, the evidence that satisfies it, and the failure mode if it is missing.
0805	0805 eventual consistency	State, durable truth, and reversibility	reviewed	Agreement postponed rather than denied. Shadow: stale reads treated as if they were fresh truth.	stale reads treated as if they were fresh truth.	Before editing, state the eventual consistency obligation, the evidence that satisfies it, and the failure mode if it is missing.
0825	0825 latency	Runtime pressure, behavior, and operational physics	reviewed	The delay before useful work reaches the caller. Latency is what users feel even when throughput graphs look flattering.	when averages hide tail pain and the slow path becomes the real product.	Before editing, state the latency obligation, the evidence that satisfies it, and the failure mode if it is missing.
0848	0848 quorum	State, durable truth, and reversibility	reviewed	Not everyone must agree, but enough must. This word turns distributed action into a threshold question instead of a unanimous fantasy.	when the quorum proves agreement among nodes but not correctness of the value.	Before editing, state the quorum obligation, the evidence that satisfies it, and the failure mode if it is missing.
0898	0898 commit {DB}	State, durable truth, and reversibility	reviewed	The moment a proposed change becomes durable history. Shadow: writing too early, before the world is actually ready to carry the new truth.	writing too early, before the world is actually ready to carry the new truth.	Before editing, state the commit obligation, the evidence that satisfies it, and the failure mode if it is missing.
0926	0926 migration	State, durable truth, and reversibility	reviewed	Stored reality changing shape without being lost. Good migrations are staged, inspectable, and reversible long enough to discover what the data actually contains.	when irreversible data movement starts before dirty cases and compatibility windows are known.	Before editing, state the migration obligation, the evidence that satisfies it, and the failure mode if it is missing.
0943	0943 rollback {DB}	State, durable truth, and reversibility	reviewed	Permission to retreat toward a previously trusted state. A system without rollback mistakes hope for safety.	when the rollback path exists on paper but cannot restore the actual user-visible state.	Before editing, state the rollback obligation, the evidence that satisfies it, and the failure mode if it is missing.
0974	0974 attestation	Observation, release, and proof surfaces	reviewed	A proof that a thing is what it claims to be or was produced the way it claims. It matters most when trust cannot be assumed.	when a signed claim is trusted without checking issuer, scope, freshness, or revocation.	Before editing, state the attestation obligation, the evidence that satisfies it, and the failure mode if it is missing.
0976	0976 authenticate	Authority, trust, and named shadows	reviewed	Prove who is making the claim before deciding what the claimant may do. Shadow: trusting names that have not earned entrance.	trusting names that have not earned entrance.	Before editing, state the authenticate obligation, the evidence that satisfies it, and the failure mode if it is missing.
0978	0978 authorization	Authority, trust, and named shadows	reviewed	After identity is known, what acts are permitted? Shadow: accidental omnipotence hidden behind a successful login.	accidental omnipotence hidden behind a successful login.	Before editing, state the authorization obligation, the evidence that satisfies it, and the failure mode if it is missing.
1007	1007 hash {Sec}	Authority, trust, and named shadows	reviewed	Arbitrary input reduced to a fixed fingerprint. Use it for identity, integrity, bucketing, and change detection; never mistake it for secrecy.	when hash equality is treated as meaning, authority, or secrecy it does not provide.	Before editing, state the hash obligation, the evidence that satisfies it, and the failure mode if it is missing.
1017	1017 least privilege	Authority, trust, and named shadows	reviewed	Give only the authority required for the present act, no more. It is one of the simplest words for reducing future regret.	when roles accumulate exceptions until least privilege becomes a slogan.	Before editing, state the least privilege obligation, the evidence that satisfies it, and the failure mode if it is missing.
1028	1028 policy	Authority, trust, and named shadows	reviewed	The declared rule by which a class of cases is decided. Good policy reduces arbitrary judgment; bad policy merely freezes confusion.	when policy text says one thing and enforcement code grants another.	Before editing, state the policy obligation, the evidence that satisfies it, and the failure mode if it is missing.
1050	1050 signature {Sec}	Authority, trust, and named shadows	reviewed	Identity or intent made checkable through cryptographic proof. Useful wherever trust must survive distance and replay.	when a valid signature is accepted outside its intended scope, time, or trust root.	Before editing, state the signature obligation, the evidence that satisfies it, and the failure mode if it is missing.
1073	1073 canary	Observation, release, and proof surfaces	reviewed	A deliberately limited release whose job is to discover whether production reality agrees with the story told in staging.	when the canary is too narrow to detect the failure the full population will hit.	Before editing, state the canary obligation, the evidence that satisfies it, and the failure mode if it is missing.
1086	1086 deploy	Observation, release, and proof surfaces	reviewed	The crossing from forge to world. Many good ideas become bad facts only after they are actually shipped.	when deployment is treated as success before runtime behavior and rollback are observed.	Before editing, state the deploy obligation, the evidence that satisfies it, and the failure mode if it is missing.
1088	1088 diff {Forge}	Observation, release, and proof surfaces	reviewed	A visible account of what changed between one state and another. Good diffs make review local; bad diffs turn truth into fog.	when a small diff hides a large semantic, data, or operational change.	Before editing, state the diff obligation, the evidence that satisfies it, and the failure mode if it is missing.
1146	1146 benchmark	Observation, release, and proof surfaces	reviewed	A performance claim forced to meet measurement. Benchmarks are where speed rhetoric either cashes out or dies.	when a benchmark optimizes the measured path and neglects the production path.	Before editing, state the benchmark obligation, the evidence that satisfies it, and the failure mode if it is missing.
1152	1152 contract test	Boundaries, seams, and collaboration	reviewed	A promise checked at the seam between systems. Use it when mocks are too flattering and end-to-end tests are too blunt.	when the contract test freezes provider quirks instead of public obligations.	Before editing, state the contract test obligation, the evidence that satisfies it, and the failure mode if it is missing.
1172	1172 invariant	State, durable truth, and reversibility	reviewed	A law that must remain true while the rest of the system is allowed to move. If you cannot say the invariant, you probably do not yet understand the change.	when the invariant is asserted in prose but not guarded by checks or tests.	Before editing, state the invariant obligation, the evidence that satisfies it, and the failure mode if it is missing.
1180	1180 observability	Observation, release, and proof surfaces	reviewed	Enough internal evidence exists that you can infer what the system is doing from the outside. Not logs alone: legible state under pressure.	when observable signals exist but no one can connect them to user impact.	Before editing, state the observability obligation, the evidence that satisfies it, and the failure mode if it is missing.
1186	1186 property-based test	Observation, release, and proof surfaces	reviewed	Instead of checking one remembered example, ask whether a law survives many generated cases. Use it when you care more about the invariant than the anecdote.	when generated cases explore input space but miss the property users depend on.	Before editing, state the property-based test obligation, the evidence that satisfies it, and the failure mode if it is missing.
1202	1202 telemetry	Observation, release, and proof surfaces	reviewed	Measurements leaving the system in a form other systems can compare, store, and alert on. Shadow: metric exhaust without explanatory power.	metric exhaust without explanatory power.	Before editing, state the telemetry obligation, the evidence that satisfies it, and the failure mode if it is missing.
1204	1204 trace {Proof}	Observation, release, and proof surfaces	reviewed	A preserved path through execution. Use it when the question is not only what failed, but where the causal thread first bent.	when trace detail becomes noise and the causal path still remains unclear.	Before editing, state the trace obligation, the evidence that satisfies it, and the failure mode if it is missing.
1281	1281 throughput	Runtime pressure, behavior, and operational physics	reviewed	How much useful work the system can push through a narrow world in bounded time. Shadow: chasing bulk capacity while tail latency burns the user.	chasing bulk capacity while tail latency burns the user.	Before editing, state the throughput obligation, the evidence that satisfies it, and the failure mode if it is missing.
1425	1425 atomic	State, durable truth, and reversibility	reviewed	No halfway state is allowed to leak across the line. Use it when partial success would be indistinguishable from corruption.	when one layer promises indivisibility that another layer can still interleave.	Before editing, state the atomic obligation, the evidence that satisfies it, and the failure mode if it is missing.
1445	1445 deterministic	State, durable truth, and reversibility	reviewed	Given the same inputs, the same result should return. This is the antidote to drift, heisenbugs, and unreviewable behavior.	when deterministic output makes a wrong assumption reproducible instead of correct.	Before editing, state the deterministic obligation, the evidence that satisfies it, and the failure mode if it is missing.
1461	1461 idempotent	State, durable truth, and reversibility	reviewed	The word that makes retries survivable: same request, same lasting effect. Shadow: duplicate charges, duplicate emails, and fear of recovery.	duplicate charges, duplicate emails, and fear of recovery.	Before editing, state the idempotent obligation, the evidence that satisfies it, and the failure mode if it is missing.
1462	1462 immutable	Runtime pressure, behavior, and operational physics	reviewed	Once written, this thing does not change in place. Immutability buys clarity, replayability, and safer sharing at the cost of update convenience.	when immutability is shallow and hidden references still mutate underneath.	Before editing, state the immutable obligation, the evidence that satisfies it, and the failure mode if it is missing.
1467	1467 linearizable	Observation, release, and proof surfaces	reviewed	Every operation behaves as though it took effect at one real instant visible to all observers. Use it rarely, but mean it fully.	when a linearizable claim ignores the boundary, clock, or failure mode where order breaks.	Before editing, state the linearizable obligation, the evidence that satisfies it, and the failure mode if it is missing.
1472	1472 memory-safe {Qual}	Runtime pressure, behavior, and operational physics	reviewed	A promise that the system will not casually trespass across allocation boundaries. Shadow: leaks, corruption, and security bugs born from illegal touch.	leaks, corruption, and security bugs born from illegal touch.	Before editing, state the memory-safe obligation, the evidence that satisfies it, and the failure mode if it is missing.
1481	1481 pure	Runtime pressure, behavior, and operational physics	reviewed	Same inputs, same output, no hidden state smuggled in from the side. Use it to shrink reasoning scope.	when a pure-looking function reads hidden state, time, randomness, or external effects.	Before editing, state the pure obligation, the evidence that satisfies it, and the failure mode if it is missing.
1492	1492 serializable {Qual}	State, durable truth, and reversibility	reviewed	Concurrency forced to behave as though transactions happened in one clean order. Expensive when overused, indispensable when history must remain sane.	when serializable language hides weaker isolation, contention, or retry behavior.	Before editing, state the serializable obligation, the evidence that satisfies it, and the failure mode if it is missing.
1546	1546 leak {Curse}	Authority, trust, and named shadows	reviewed	Something escapes the boundary that should have held it: memory, secrets, file descriptors, authority, abstraction, or time.	when treating a leak as the cause prevents finding the owner, lifetime, or boundary.	Before editing, state the leak obligation, the evidence that satisfies it, and the failure mode if it is missing.
1561	1561 race	Authority, trust, and named shadows	reviewed	An ordering curse: outcomes depend on timing you do not actually control. Name the race and the system becomes debuggable again.	when the race is patched locally while the shared state contract remains undefined.	Before editing, state the race obligation, the evidence that satisfies it, and the failure mode if it is missing.
1564	1564 retry storm	Authority, trust, and named shadows	reviewed	Recovery logic amplifying failure instead of containing it. Unguided retries can turn a partial outage into a self-made siege.	when retries synchronize into an outage amplifier rather than a recovery path.	Before editing, state the retry storm obligation, the evidence that satisfies it, and the failure mode if it is missing.
1567	1567 schema drift	Authority, trust, and named shadows	reviewed	The stored world and the assumed world have silently stopped matching. This is how migrations keep hurting after everyone thinks they are done.	when schema changes are shipped without compatibility checks, migration windows, or readers.	Before editing, state the schema drift obligation, the evidence that satisfies it, and the failure mode if it is missing.