# External API Integration > Use for external HTTP provider or webhook contracts, bounded retries, request identity, ambiguous outcomes, authentication, or reconciliation. - Skill: `dankosik/external-api-integration` (Agent Skill, multi-file: 5 files) - Install (CLI): `npx skillmds@latest add dankosik/external-api-integration` - Raw SKILL.md: https://api.skillmd.com/api/skills/dankosik/external-api-integration/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Integrations & APIs - Author: Dankosik (https://skillmd.com/u/dankosik) - Updated: 2026-09-22 - Page: https://skillmd.com/skills/dankosik/external-api-integration --- # External API Integration **Boundary.** A provider can commit an effect while its response is lost. Keep operation identity and evidence from request through callback/poll and reconciliation; an HTTP client alone is not an end-to-end contract. ## Match scope and authority For a whole side-effecting flow, readiness, migration, replay or recovery redesign, cover the full in-scope boundary. For review/diagnosis or a narrow correction, follow the affected stage and safety-relevant dependencies. Side-effect-free reads need only their actual contract, bounded attempt and result handling unless another stage matters. Preserve accepted architecture outside the requested change. Review, diagnosis and design are read-only. Build/fix permits in-scope local changes and safe checks, followed by repair of introduced failures. Real provider effects, credential/scope changes, webhook registration, production replay and authoritative/destructive synchronization need exact environment, account, operation set and bounds authorization. Preflight and freshly verify approved actions; credentials and tools are not permission. Keep real tokens, codes, signed payloads and sensitive bodies out of fixtures, logs and reports. Use current official provider/version evidence when it can change the decision. Distinguish documented guarantees, observations, local choices, inferences and gaps. Ask only for missing input affecting authority, effect identity, correctness or duplicate risk that available evidence cannot resolve. ## Load relevant mechanics - [HTTP resilience](references/http-resilience.md) for attempt loops, transport phases, rate limits, polling or resumable pagination. - [Authentication](references/authentication.md) for OAuth/token lifecycle, credential binding or rotation; a static credential alone does not require a lifecycle redesign. - [Webhooks](references/webhooks.md) for receiver authentication, raw envelope, durable acknowledgement, ordering and callback recovery. Use only applicable sections and checks. A timeout-parser change does not require all three documents, sandbox provisioning or a new end-to-end platform. An explicit runnable-test request still needs real test source, setup and assertions. ## Pin the affected contract Identify provider, account/environment, operation, API/SDK version, request/response shape, authentication/audience, error meanings, limits and evidence origin. Add idempotency scope/retention, callback, pagination or lookup semantics when used. A sandbox demonstrates only what it exercises, not production quotas or effects. For interacting side effects keep one boundary ledger; a narrow task may use a single row or equivalent prose: | Effect or sync | Provider evidence | Local invariant | Identity/checkpoint | Deadline/acceptance | Ambiguity/recovery | Inference or gap | Authority | | --- | --- | --- | --- | --- | --- | --- | --- | Choose synchronous completion when the caller needs it and the full deadline allows it; otherwise a durably accepted pending operation may need independent observation. Do not reopen that accepted choice for an unrelated field change. Pin callback versions separately where supported. Tolerate documented additive fields but retain an incompatible/owned failure for an unknown required schema, state or signature version; do not invent familiar meaning. ## Identity, attempts and outcomes Give an intended side effect a stable operation ID before attempting it. Retain provider/environment binding, canonical intent, idempotency scope/expiry and request/resource IDs needed for lookup. Retries keep equivalent intent and the same identity; a newly requested effect gets a new one. Prevent concurrent workers from creating independent provider operations for the same local intent. Without documented idempotency or proof of non-transmission, disable automatic after-possible-send retries for side effects. Resolve provider state, a supported reconciliation key or compensation policy rather than treating a timeout as non-execution. HTTP status alone does not prove retry safety. Budget queueing, authentication, DNS/connect/TLS, sending, headers/body, backoff and parsing inside an end-to-end deadline. Bound attempts, response/decompression size and quota-scoped concurrency; cancellation reaches waits and I/O. Independent reconciliation can outlive a caller only with its own owner and budget. Honor provider retry delays only within those limits. Keep operationally distinct outcomes: succeeded with authoritative evidence; permanent requiring change; retryable with safe identity and remaining budget; ambiguous after possible effect; incompatible when the contract cannot be read safely. Preserve redacted phase/request evidence. Unknown effect state is not a successful or permanently failed business result. ## Observe and reconcile Use the authoritative lookup or authenticated callback the provider supports. Poll a status endpoint rather than repeating the write. Correlate by local and provider identity; timestamps or arrival order do not create undocumented ordering. Reconciliation handles overdue, ambiguous, failed-callback and divergent records within a lookback/checkpoint contract. Apply only permitted transitions and keep unresolved or incompatible cases visible and owned. Page checkpoints cannot skip undurable item effects; replay must preserve identity, including permanent item failures and deletion semantics. A single safe read does not need an invented reconciliation daemon. ## Prove the claim and finish Select evidence for the changed mechanism: contract fixtures for payloads and classification; scripted transport/time for retries and ambiguous phases; a provider sandbox for its actual behavior; an end-to-end flow for a cross-stage claim. These are alternatives or complementary checks, not four mandatory stages for every correction. Real webhook authentication requires the exact signed bytes and provider scheme, not a mocked authenticated result. A full side-effecting readiness or migration assessment must cover each ledger row's identity, durable commits, uncertainty, bounded recovery, failure tests, signals and authority. Rollout needs old/new routing ownership, canary/stop rules, quota headroom and rollback that retains recovery for in-flight effects. Stopping new routing does not erase existing external work. Use bounded-cardinality metrics; keep operation IDs in appropriate redacted logs/traces instead of labels. Complete diagnosis/design at its requested fidelity, marking unrun proofs. Complete a local fix with applicable project checks and introduced-failure repair; reuse valid same-revision/environment evidence. Missing sandbox or live evidence limits the guarantee, not unrelated work. Do not create new accounts, credentials or test platforms to satisfy an invented completion gate. Lead with verdict, affected contract, cause/decision, correction, proof and limits. Use ready/not-ready only for the readiness actually being assessed; a completed analysis is not a claim of production readiness. Distinguish proposed, implemented locally, sandbox-tested, deployed and verified live. Public API, business ledger, messaging and database concerns keep their own owners. Use `reliable-messaging`, `postgres-schema-design`, `postgres-performance` or `auth-access-control` for a distinct unresolved question, not as compulsory calls. Pass identity, invariant and evidence without redesigning excluded internals.