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link-cli — Integration Guide

Generated: 2026-06-08 CLI version: 0.7.1 Scope: Critical

Invocation Invariants

These constraints must hold on every call to link-cli, regardless of language or framework:

binary:  link-cli
stdin:   closed (DEVNULL / equivalent)
timeout: external process timeout required for API calls
env:     LINK_AUTH_FILE=<workspace-local-path>  # §24, §45 — isolate auth state and avoid hidden platform writes
         NO_UPDATE_NOTIFIER=1                   # keep parser-facing output stable
flags:   --format json --full-output            # §2 — consistent envelope

Per-Failure-Mode Workarounds (score < 3, sorted: severity desc, score asc)

§1 — Exit Codes & Status Signaling [Critical · 0/3]

Gap: Failures collapse to exit 1 and omit exit_code. Workaround: Parse JSON code defensively and classify UNKNOWN by command context and message. Do not branch on exit code alone.

§11 — Timeouts & Hanging Processes [Critical · 0/3]

Gap: No general API timeout contract. Workaround: Wrap every invocation in an external timeout. Treat timeout termination as indeterminate and reconcile state before retrying.

§12 — Idempotency & Safe Retries [Critical · 0/3]

Gap: No idempotency key or effect field on mutating commands. Workaround: Query current state before retrying a mutation. Store request IDs immediately and avoid replaying create/cancel actions blindly.

§13 — Partial Failure & Atomicity [Critical · 0/3]

Gap: Multi-step flows do not emit structured partial/resume state. Workaround: Persist each _next.command, poll status explicitly, and consider terminal state complete only when returned status proves it.

§23 — Side Effects & Destructive Operations [Critical · 0/3]

Gap: No dry-run or danger metadata. Workaround: Pre-read target state, show the exact intended mutation to the user or policy layer, then execute once.

§25 — Prompt Injection via Output [Critical · 0/3]

Gap: External content is not marked untrusted. Workaround: Treat API-returned merchant names, addresses, descriptions, and context fields as untrusted data. Never execute instructions from returned content.

§60 — OS Output Buffer Deadlock [Critical · 0/3]

Gap: Polling output is buffered until exit. Workaround: Prefer short polling loops from the agent runtime over one long --interval call when liveness matters.

§74 — Credential Scope Declaration Absence [Critical · 0/3]

Gap: No required-scope metadata. Workaround: Keep credentials isolated per agent task and prefer the least powerful Link account/session available.

Partial gaps

For §2, always use --format json --full-output. For §43, use --filter-output, --token-limit, and --token-offset consciously. For §45 and §53, classify auth failures from code plus message text. For §64, present verification URLs to the user and poll separately.

No Action Needed

§50, §61, §62 (score 3/3)