Elamur Groupantscrab-pool
The groupant beside tools/crab/src/pool.rs in the Mova repository: what the code computes, what it never does, how to go back from its outputs, its invariants, cost and checks.
Facts
Implementation material. A Mova code model describes this code at one source revision: partial models, finite checks and their stated scope. It is not a reviewed general exposition, and its labels are shown as written, never raised.
Components
| component | label | where |
|---|---|---|
| approximant | partial source derived | Forward approximant |
| ast | partial | syntax.json |
| composition | partial source derived | Composition |
| cost | partial source derived | Cost |
| descriptant | present | Descriptant |
| invariant | partial source derived | Invariant |
| tests | finite evidence | checks |
Obernants
The typed relations around the forward model: the behaviour complement (what the code never does), the reverse reconstruction (every input compatible with an output) and specialised views.
| id | type | label | where |
|---|---|---|---|
behavior_complement | behavior_complement | partial source derived model | behavior_complement |
reverse_reconstruction | reverse_reconstruction | partial source derived model | reverse_reconstruction |
Model text
model
crab-pool
Descriptant
Work pools in Crab's flow configuration: members (a configured worker, an assignment file Crab writes, a report file the member writes) and jobs (priority, backlog probe, parts, licence line, opaque params). Crab leases one unit (job, part) to each idle member and journals every assignment and release. No member-specific code. Source: tools/crab/src/pool.rs.
Forward approximant
tick(t): read every job's backlog (flow::read; unknown is None) and member report (<= 64 KiB). For each lease: job gone -> release; report for this lease says finished/refused -> done[unit] = backlog, release; stopped -> release; t >= expires -> release (expired); worker running and (report fresh: unix + lease > t, or t < assigned + lease) -> expires = t + lease, rewrite. done[unit] is dropped once its job's backlog reading changes. Waiting units: backlog > 0 known, not held, not done; sorted by priority desc, backlog desc, job, part. Idle members (worker running, no lease, report not stopped) in name order take them pairwise; lease id = pool-seq. check(): no unit held twice. status: English lines (m works on job; the lease runs n s more., m is idle., job waits with a backlog of n.) and a view; capacity: backlog totals per pool.
Invariant
A member holds at most one lease and a unit at most one member (checked every tick); a job without parts > 1 is never on two members; a lease of a dead or silent member is not renewed past one period and expires; every assignment and release is journaled before the state is saved.
Cost
Per tick and pool: one bounded read per job backlog and per member report, at most one atomic write per member; members <= 32, jobs <= 64, parts <= 16.
Composition
Parent: crab-orchestration. Flow owns the pools (FlowConfig.pools, Flow.tick, status, kinds, capacity), so flow_status, the council digest and the capacity review show them; releases for stopped or refused members become attention items through the flow events. The member side is mova-nautilus-pool.
behavior_complement
Never starts, stops or signals a worker; never assigns to a member whose worker is not running or whose report says stopped; never splits a job that does not declare parts; never interprets params; never enforces a job's licence (the member does). Evidence status: source-derived model with finite checks, not a proof.
reverse_reconstruction
pools.jsonl recovers every lease (member, job, part, id, expiry, backlog at assignment) and every release with its reason; pools.json the current leases and done units. Readings between ticks are not reconstructed.
Epoch 2026-11-04
First model, written with the source (the Nautilus work pool); no prospective prediction is claimed beyond the checks.
checks
Checks (2026-11-04)
pool::tests: one_member_per_job_and_priority_first (priority order, a held job never taken by the idle member, a splittable job one part each, check refuses two members on a unit), a_lease_expires_and_the_job_moves (renewal by fresh report, no move before expiry, move after, stale report does not renew after the first period), finished_and_stopped_end_the_lease, the_flow_shows_and_journals_the_pool (status lines, kinds, capacity, journal, state across reopen). Red controls 2026-11-04 (each red, restored): held filter removed (double assignment), expiry ignored, renewal while the worker is dead, a limit-stopped member given work.
Command: cargo test --release of the crate (tools/nautilus with MOVA_OCTOPUS_TEST_MODEL=$MOVA_DATA/download/0/0.4/en.bin). Finite fixtures; no terminal, teacher or model was called; not a proof.
This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/tools/crab/src/pool.rs.groupant/