[AbirAbbas]

A1a of the Workstreams move: workstream logic now lives in the desk, the engine stays the AI harness (design: the Workstreams plan's ARCH-DESIGN §1, row A1a).

Summary

• New pure-Rust crate crates/workstreams (workstreams-core), no Tauri types. One SQLite file per engine home (store_path: <app data>/workstreams/<16 hex of sha256(engine home)>/workstreams.db, WORKAF_WORKSTREAMS_DB overrides) with canvas's habits: rusqlite 0.37 bundled, WAL, user_version migrations under BEGIN IMMEDIATE, a newer file refused untouched, a 10 s writer wait mapped to busy.
• Schema v1 holds workstreams (with name and collection_id), member-job claims (UNIQUE(factory, job)), pending creates, plans, pages with versions and deleted state, records, go-aheads, sources, suggestions, suggestion edits, wakes and wake items.
• All 36 contract v0.5 methods as Store methods named like the Backend methods, taking and returning the contract's serde types, with its errors (not_found, conflict, version_conflict + detail, too_large, bad_params, in_other_workstream + detail, cycle, busy), stage rule, size limits, Read-by-jobs defaults and go-ahead rules.
• Engine facts are inputs: job states, job costs and agent spend come through the EngineFacts trait, read outside any transaction; ChangeSink receives one workstream.changed per changed workstream after commit; page documents go through the PageDoc seam (A1b's crate implements it).
• Agent-attributed domain operations for A3 (by_agent, agent page writes, proposals, suggestion create, source proposals; Done checked inside the write) and the wake store for A4 (begin_wake with key dedup and daily caps, settle_wake, expire_wakes, parse_wake_answer).
• The serde types moved from crates/core/src/engine/workstreams.rs into the crate; ui2-core re-exports them, so no import changes. Outside the crate: the workspace member line, the core dependency line, the re-export and Cargo.lock.
• No Backend method is switched (A2 does that); no markdown renderer (A1b).

Validation contract

item	tests
(a) every local method behaves as the contract says, every error code	tests/appworkstreams*.rs, pages.rs, records_goaheads.rs, sources.rs, suggestions.rs, wakes.rs, method_refusals.rs (each of the 36 methods: its own not_found and bad_params)
(b) the engine's store tests, ported	one Rust test per Go test in internal/workstream/*_test.go (store, pages, records/go-aheads, limits, sources, agent, agent-done, v0.2 fields, suggestions, wakes, wake answer, wake fix 1/2) and the store parts of cmd/codeaf/appworkstreams*_test.go; each names its Go origin and contract item
(c) the store never needs the engine	validation.rs engine_facts_are_the_only_number_inputs_and_run_outside_locks, review_fix1.rs finding 3
(d) schema v1 migration idempotent	validation.rs migration_is_idempotent_across_store_handles, newer_schema_is_refused_without_changing_database_bytes
(e) one workstream per job	validation.rs one_workstream_per_job_is_enforced_by_every_door_and_sqlite, store.rs ownership tests
(f) keep→grant atomic	validation.rs keep_grant_is_atomic_when_the_member_job_disappears, workstream_fields_v02.rs keep refusals and rollback
(g) size limits	limits.rs, validation.rs row_and_page_parameter_bounds_refuse_atomically, source and suggestion caps
(h) shape test against the contract examples	contract_shapes.rs: reads docs/workstreams-wire.md itself (examples and field tables), sends every example's params through the store, checks result, error and event shapes; fails on an unused example or a method with no case

Review: one fresh review round (2 major, 3 minor), all fixed with tests (review_fix1.rs, method_refusals.rs).

Left for others

• A2: implement PageDoc for A1b's crate and re-run the markdown-sensitive tests with it; feed EngineFacts from collections.open / factory.queue / agents.open; route ChangeSink into the engine-event delivery; create orchestration (pending_create, collections.create, agents.create, close an unused agent); claim_jobs/release_jobs on collections.add/remove, replace_jobs at start; collections.rename first, then set_name; origin-chat check; map WorkstreamError to EngineError.
• A3: tool scoping and source read-safety before calling the agent operations. A4: the scheduler (08:00 slot) on top of begin_wake/settle_wake/expire_wakes; whether errand costs already land in the agent's spent_usd (never count wake costs twice).
• Engine schema 3–6 compatibility tests are not ported: the desk does not import engine files (design §6).

Contract changes

None. docs/workstreams-wire.md is unchanged.

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