Ollama 0.11.8 segfaults on any Pydantic-shaped structured-output schema
with $ref, anyOf, or pattern — confirmed on the deploy host with the
simplest MVP case (BankStatementHeader alone). The earlier null-stripping
sanitiser wasn't enough.
Switch to format="json", which is "emit valid JSON" mode. We're already
describing the exact JSON shape in the system prompt (via GenAIStep +
the use case's citation instruction appendix) and validating the
response body through Pydantic on parse — which raises IX_002_001 on
schema mismatch, exactly as before.
Stronger guarantees can come back later via a newer Ollama, an API
fix, or a different GenAIClient impl. None of that is needed for the
MVP to work end to end.
Unit tests: the sanitiser left in place (harmless, still tested). The
"happy path" test now asserts format == "json".
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Ollama 0.11.8's llama.cpp structured-output implementation segfaults on
Pydantic v2's standard Optional pattern:
{"anyOf": [{"type": "string"}, {"type": "null"}]}
Confirmed on the deploy host: /api/chat request with the MVP's
ProvenanceWrappedResponse schema crashed Ollama with SIGSEGV; the client
saw httpx RemoteProtocolError → IX_002_000.
New _sanitise_schema_for_ollama walks the schema recursively and drops
"type: null" branches from every anyOf. Single-branch unions are
inlined so sibling keys (default, title) survive. This only narrows
what the LLM is *told* it may emit; Pydantic still validates the real
response body against the original schema and accepts None for
Optional fields if they were absent or explicitly null.
Existing unit tests updated: the "happy path" test no longer pins the
format to `_Schema.model_json_schema()` verbatim — instead it asserts
the sanitisation effect on a known-Optional field.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Real GenAIClient for the production pipeline. Sends `format=<pydantic JSON
schema>`, `stream=false`, and mapped options (`temperature`; drops
`reasoning_effort`). Content-parts lists joined to a single string since
MVP models don't speak native content-parts. Error mapping per spec:
connection/timeout/5xx → IX_002_000, schema violations → IX_002_001.
`selfcheck()` probes /api/tags with a fixed 5 s timeout for /healthz.
Tests: 10 hermetic pytest-httpx unit tests; 2 live tests gated on
IX_TEST_OLLAMA=1 (never run in CI).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
