[isomorphisms]

Extends the explicit affine-plane probe so frozen fit/development/held-out membership is independent of semantic labeling.

The existing probe already excluded labeled development and held-out examples. Private Takeout work exposes the missing boundary: a development/held-out row can be intentionally unlabeled, and without a separate partition map it would still be eligible for provisional-unlabeled sampling.

This change:

• adds an optional complete id, partition TSV with fit, development, and held_out
• excludes all non-fit partition rows from plane fitting and provisional-unlabeled sampling
• rejects semantic label roles that disagree with the partition map
• records partition provenance and counts in the probe report
• preserves existing behavior when no partition map is supplied
• adds a synthetic positive fixture plus a targeted known-bad label/partition mismatch fixture
• runs that check in the existing body-hyperplane workflow

Exact-head evidence at 0602f7410c27aa81bd68cc3904cf34e2cec46f7e, workflow run 35339745385:

• body-input hook: success
• unlabeled partition isolation fixture: success
• public paper-body staging: success
• pinned mxbai ONNX embedding: success
• positive/unlabeled affine-plane fit: success
• existing isolation/frozen-policy summary: success
• derived-evidence artifact publication: success

The earlier run at 857cc99c... failed before the fitter because the new test harness dynamically imported the module without registering it in sys.modules; that harness defect was repaired without changing the partition contract.

This is mechanics/isolation work only. It does not change the frozen proposal threshold or claim improved semantic quality.

Accumulated scope at the current head

Current head 7387b1b0adeb6f04825b64420b8db31db9d1a56d also contains isomorphisms/IB PR #68, “Declare external hyperplane text representations” (#68), merged into this branch at that exact commit. This history is recoverable: the partition boundary is 405387093eba3e4c584f9d54e7768538b08a7f82 through 0602f7410c27aa81bd68cc3904cf34e2cec46f7e; the external representation boundary is d49159ac565b424749967785c0a53a61180fea1f, its contract fixtures af886a544271d06f31ecdc9a9800fdd2c02f931f, its documentation b3f17106c1cb24024ea003f5d36976cb32ce27cf, and its CI coverage 29fedb0393135aa0135589d18518469b8d2a912f.

The accumulated four-file diff therefore covers both independent fit/development/held-out membership and explicit declared-text external input contracts. The default body-only contract remains body-only; external representations must declare their kind/model-text fields and retain exact input/embedding provenance. The SVM, threshold, votes, partitions and evaluation mechanics are not changed by the external-contract child. This is not a semantic-quality or private-corpus acceptance claim.

The intended base remains the Pensieve parent branch 0.2/pensieve-arxiv. Its live head 2f395e49b2eddd1379af8818cf58425fc333fed9 has advanced and is not an ancestor of this child head; current-head green fixtures do not qualify that untested integration. This reconciliation updates the description only. The PR remains draft and no merge is requested by its prior passing fixtures.

Retirement result — 2026-10-06

Merged into the Pensieve family branch at 2fc74f2 under the authorized retirement sweep. Exact child head 7387b1b is preserved. Before merge, integration with parent 2f395e4 was conflict-free and local shell smoke, deterministic arXiv round trip, Pensieve hyperplane hook, and positive/known-bad partition plus external representation fixtures passed. These use the inherited compatibility interpreter/Python experiment boundary; actual Grease execution and semantic-quality/private-corpus acceptance are not claimed. One Pensieve successor remains: isomorphisms/ib PR #46, “Begin IB 0.2 as a shell-first Pensieve” (#46).