docs: implementation plan (TTY precedents folded in); task decomposition (17 tasks)

Plan updated with the alknet-tty findings: the drainer pattern
(single ordered writer) makes outbound chunk-boundary parsing sound;
TestStdinSink's try_send→Full→Pending is the inbound backpressure
precedent; OQ-01(a) now cites the reference.

Task graph (taskgraph-validated, 17 tasks, 6 generations, no cycles):
- tasks/server/: core-types, auth, healthz-decoy, adapter
- tasks/gateway/: dispatch, routes, publish
- tasks/websocket/: byte-adapter (research POC), upgrade-session, overlay-ops
- tasks/adapters/: from-openapi, from-jsonschema, to-openapi, from-wss, mcp
- tasks/client/: http-host
- tasks/infra/: integration-suite (phase 4)

Critical path runs through server core → adapter → WS session →
overlay tests → integration suite. High-risk tasks are the three WS
tasks, de-risked by the ws-byte-adapter POC blocking upgrade-session.

tasks/adapters/from-openapi.md

@@ -0,0 +1,47 @@
+---
+id: adapter-from-openapi
+name: from_openapi adapter (parse + forwarding handlers)
+status: pending
+depends_on: [client-http-host]
+scope: broad
+risk: medium
+impact: component
+level: implementation
+tags: [adapters, phase-3]
+---
+
+## Description
+
+Port `adapters/from_openapi.rs` (~2k lines, the largest port) from
+`/workspace/@alkdev/alknet/crates/alknet-http/src/adapters/from_openapi.rs`:
+OpenAPISpec (from_json/from_yaml/from_str JSON-first per ADR-051,
+from_value), $ref resolution, HttpServiceConfig, per-op
+HandlerRegistration construction (Internal by default, FromOpenAPI
+leaf provenance), forwarding handlers (path-template substitution,
+query params, auth header from capabilities, content-type branching),
+SSE→StreamingHandler for Sub ops (HandlerKind::Stream), error fidelity
+(`HTTP_<status>` codes). Type paths move to alkcall::client (adapter
+contract) and alkcall::registry.
+
+## Acceptance Criteria
+
+- [ ] JSON + YAML + from_str detection ports with tests
+- [ ] Handler construction: Query/Mutation→Once, Sub→Stream; Pub never produced (v1)
+- [ ] Forwarding: path params, query params, auth injection from Capabilities, error mapping — unit tested (mock HTTP via local axum server)
+- [ ] No env-var reads
+- [ ] `cargo test` passes
+
+## References
+
+- docs/architecture/http-adapters.md (§from_openapi, §Forwarding handler, §Error Fidelity)
+- docs/architecture/decisions/023-operation-error-schemas.md, 051-yaml-input-for-from-openapi.md
+- Old source: `/workspace/@alkdev/alknet/crates/alknet-http/src/adapters/from_openapi.rs`
+
+## Notes
+
+> Agent fills during implementation. Largest single port — consider
+> splitting internally (parse half / handler half) if review flags it.
+
+## Summary
+
+> Agent fills on completion.