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Library / First Principles Framework (FPF) - Core Conceptual Specification
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A.6.B:8.4.3 - Example 1 — Software engineering (SLO-ish API latency)
A.6.B:8.4.3.1 - Draft sentence (non-conformant)

“This API guarantees p95 latency < 200ms.”

A.6.B:8.4.3.2 - Atomize + Classify (L/A/D/E)

L-API-01 (Definition). p95_latency(window W, population P, unit U, method M) is defined as … (formal measurement definition). (Lives in Signature.Laws or a referenced measurement definition pack.)

L-API-02 (Interface signature). The API endpoints and parameters are as declared (including parameter passing discipline / units). (Signature-level structure.)

A-API-01 (Gate predicate: admissibility). The claim “p95 < 200ms” is admissible only under declared load profile + deployment region + sampling method + window: AdmissibleLatencyClaim := (region=US) ∧ (concurrency≤X) ∧ (payload≤Y) ∧ (W=5m) ∧ (M=HDRHistogram@v…) ∧ (P=requests that match filter F) (References L-API-01 for definition.)

D-API-01 (Commitment). Admitted service-maintaining system ServiceOperations-A is the actual duty bearer of separately obtaining LatencyCommitment-API-01 : U.Commitment; under that commitment it SHALL meet p95_latency < 200ms when A-API-01 holds, adjudicated per L-API-01 using the carriers and observation conditions in E-API-01. (References L-API-01 and A-API-01 by ID; does not restate them.)

D-API-02 (Operational duty). Admitted operations system SRE-A is the actual duty bearer of separately obtaining IncidentNoteCommitment-API-02 : U.Commitment; it SHALL publish incident notes when LatencyCommitment-API-01 is violated and SHALL avoid claiming compliance outside A-API-01. (References D-API-01 and A-API-01 by ID.)

E-API-01 (Evidence / carriers). For LatencyEvaluation-T1 over Γ_time=[t1..t2], actual carriers TraceBatch-T1, Histogram-H1, DashboardSnapshot-D1, and SamplingConfiguration-S1 were produced or observed under the operating and sampling conditions in A-API-01, using the metric and computation definition in L-API-01. An A.10 evidence-provenance path links those exact carriers to LatencyEvaluation-T1 and its LatencyResult-T1. (References A-API-01 and L-API-01 for the operating conditions and metric definition.)

D-API-03 (Duty-to-evidence linkage). Admitted telemetry-maintaining system TelemetryOperations-A is the actual duty bearer of separately obtaining TelemetryRetentionCommitment-API-03 : U.Commitment; it SHALL retain or expose the actual carriers referenced in E-API-01 for the audit window required by policy. (References E-API-01 by ID.)

E-API-02 (Observed value claim). For interval Γ_time = [t1..t2] under conditions pinned to A-API-01 and using carriers in E-API-01, LatencyEvaluation-T1 produced LatencyResult-T1 with observed p95_latency = 173ms (computed per L-API-01). (References A-API-01, L-API-01 and E-API-01.)

A.6.B:8.4.3.3 - Triangle decomposition (explicit)
  • A-API-01 is “the predicate”.
  • D-API-01 → A-API-01 states the commitment under the gate or envelope.
  • E-API-01 → A-API-01 binds adjudication (carriers used to decide the gate or commitment).
  • D-API-03 → E-API-01 expresses retention and exposure obligations for those carriers.
A.6.B:8.4.3.4 - Readable recomposition

Tech recomposition (L/A/D/E-classified claim bundle, short):

  • L-API-01 defines p95 latency computation.
  • A-API-01 specifies when the latency claim is admissible.
  • D-API-01 states the commitment under that envelope.
  • E-API-01 lists adjudicable carriers and conditions used to adjudicate A-API-01.
  • D-API-02 states the operational incident-note duties.
  • D-API-03 states the retention and exposure duties for carriers in E-API-01.
  • E-API-02 reports observed performance under A-API-01 for Γ_time=[t1..t2].

Plain recomposition (one paragraph, readable): “The API’s latency target uses the p95 definition in L-API-01, and the mechanism admits its evaluation only under operating envelope A-API-01. ServiceOperations-A has the latency duty stated in D-API-01. Adjudication uses the telemetry carriers listed in E-API-01; TelemetryOperations-A has the retention duty in D-API-03, and SRE-A has the incident-note duty in D-API-02. Under that envelope, the observed p95 over Γ_time=[t1..t2] was 173ms (E-API-02).”