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SciMesh/docs/sdk-handoff.md
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2026-08-01 23:22:20 +03:00

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# Workload SDK handoff
**Audience:** the engineer/AI continuing SciMesh Workload SDK implementation.
**Date:** 2026-08-01. **Baseline:** uncommitted working tree on `main` (`11e9333`
plus the CTX-16 SDK changes); `python -m pytest -q` reports **225 passed**.
Read first, in this order: `AGENTS.md` (binding repo rules),
`docs/scimesh-sdk-roadmap.md` (delivery order — it governs, this file does not),
`docs/scimesh-sdk-contract.md` (normative target semantics),
`docs/workload-sdk.md` (author guide for what exists), and the CTX-16 entry in
`PLAN.md`.
## What is already done (do not redo)
CTX-16 "Workload SDK foundation" is complete and tested. `scimesh/sdk/`
implements the `core-batch-v1` profile:
- Immutable, JSON-strict value objects: `identity.py`, `artifacts.py`,
`workflow.py`, `manifest.py`, `plans.py`, `execution.py`, `resources.py`.
- Fail-closed compatibility negotiation: `runtime.py` (`negotiate_manifest`)
plus request-level checks in `registry.py`.
- Installed-package registry with administrator allowlist, exact version +
`sha256:` digest pinning, entry-point discovery with digest measured before
and after import: `registry.py`, `integrity.py`.
- Verifier primitives `ExactArtifactVerifier`, `CanonicalRecordVerifier`,
`NumericToleranceVerifier` with bounded sanitized evidence: `verification.py`.
- Local conformance harness: `LocalArtifactStore`, `LocalCoreBatchExecutor`,
`ResourcePool` (atomic all-or-nothing reservation): `conformance.py`.
- Legacy adapter exposing distributed `similarity-search` through the SDK
without changing its wire schema: `compat/distributed_v1.py`, `builtins.py`;
entry point `similarity-search@1.0.0` is declared in `pyproject.toml`.
- Tests: `tests/test_sdk_{models,resources,verification,compatibility,registry}.py`
including fail-closed rejection coverage for every advanced profile
declaration (gang, GPU modes, pools, checkpoints, retries, secrets, streams,
loops, side effects).
## What remains, in delivery order
1. **`descriptor-batch` reference workload** (roadmap step 3 — the recommended
next task; it is pure Python and needs no coordinator changes). Pinned RDKit
2D descriptors, canonical one-row-per-input CSV, shard-index concatenation
with one header, byte-identical local/distributed output, two-worker quorum.
Build it as an SDK-native package (manifest + planner/runner/reducer/
verifier handlers), not through the legacy adapter; reuse the
`similarity-search` adapter (`scimesh/sdk/compat/distributed_v1.py`) and
`builtins.py` as the structural template, and the
`tests/test_sdk_compatibility.py` fixtures as the test template. This is the
intended first `untrusted_quorum` candidate (byte_exact + exact-artifact@1).
2. **Distributed `similarity-graph`** (CTX-10, roadmap step 1). The coordinator
currently rejects `similarity-graph` uploads; it needs cross-shard block-pair
planning and duplicate-safe reduction. STATUS.md names this the next
recommended assignment overall.
3. **Coordinator/Worker protocol v2** (needs CTX-10, then CTX-13 in-worker CPU
parallelism and CTX-14 GPU execution; Go + Python). The protocol-v1
coordinator persists only flat one-input/one-result tasks: no resource
requirements, stage edges, package versions, device allocations, or gang
leases. Until a versioned rollout lands, SDK declarations for those features
must stay fail-closed — do not silently "enable" them.
4. **More chemistry workloads** (roadmap step 4): standardization, SMARTS
screening, fingerprint export, fixed-template reaction enumeration, then
reaction validation/descriptors.
5. **Composite artifacts and richer verifier policies** (roadmap step 5):
first-class ordered/keyed `ArtifactCollection` edges instead of composite
manifest artifacts; decide where verifiers execute (open decision in the
roadmap).
6. **Authoring CLI** (future tooling, does not exist today): `scimesh workload
init`, `validate`, `test-local`, `test-distributed`, `golden`, `package`.
Per AGENTS.md, keep CLI parsing in workload modules and register through
`scimesh/core/registry.py`; no workload-specific logic in the main CLI.
7. **Open decisions** (listed at the end of the roadmap): SDK distribution
split, Go↔Python planner bridge, verifier execution/attestation, trust-mode
governance, multi-user enablement. Do not pick one unilaterally — surface it.
## Known traps (cost the previous session real time)
- The legacy adapter pins its own manifest (`adapter.manifest`). If a test
changes limits/workflow on the manifest, the adapter's copy must be replaced
too, or `registry.plan` fails with "planner plan does not carry the selected
immutable workload pin".
- `WorkloadDefinition` validation: a PLAN stage's `entry_point` must equal
`planner.entry_point`; every non-REDUCE stage's `entry_point` must be a key
in `runners` (REDUCE → `reducers`); verifier handlers are keyed by
`ComponentRef.canonical` and must expose a matching `.identity`.
- Negotiation requires each triggering property's feature to be declared
separately: e.g. `PROCESS_POOL` needs `process-pools` **and** `multi-process`
for `max_processes > 1`. Runtime must also advertise every declared required
feature, or negotiation fails with `feature-unavailable`.
- `feature-fallback-disallowed` in `scimesh/sdk/registry.py` is currently
unreachable via `registry.plan` (the `feature-unavailable` check fires first
for any runtime that produced a fallback). Behavior is still fail-closed;
decide whether to reorder or delete the branch.
- The local executor is deliberately trusted/in-process: it rejects anything
but `TrustMode.TRUSTED`, `NetworkPolicy.TRUSTED`, single-threaded CPU
map/reduce without retries/gangs/accelerators/secrets/checkpoints. That is a
contract, not a bug — test rejections, don't "fix" them.
- `JobRequest` parameters and failure/evidence payloads reject local paths and
URIs by design; keep new payloads location-free.
- There is a stray nested clone `SciMesh/` in the repo root (same repo at an
older commit). Ignore it and never `git add` it; consider deleting it.
- The full ChEMBL extract `chembl_37_chemreps.txt` (~2.9M rows) makes the
single-threaded local executor run for many minutes; tests must use small
TSV fixtures (see `_write_tiny_dataset`).
## Working agreement
- Verify with `source .venv/bin/activate && python -m pytest -q`; the baseline
is 225 passing tests and it must stay green. Add a regression test for every
behavioral change; similarity code needs a brute-force/sorted reference and
determinism across block sizes.
- Legacy `similarity-search` wire schema, worker alias boundary, and scientific
output must not change. Worker code never talks to PostgreSQL directly;
results go through the coordinator; failures go to `/failure`, never as
`file://`/`worker://` result URIs.
- Do not commit datasets, generated CSV/PNG, tokens, or local worker artifacts.
- One CTX task per pull request; link the CTX item from `PLAN.md`.