fix(inference): warn when modelCache.claimName is silently ignored

[joryirving]

What

Emit a ModelCacheClaimIgnored warning event when spec.modelCache.claimName is set but the cache path is inactive — caching disabled on the operator (chart modelCache.enabled: false / --model-cache-path unset) or the model has no effective cache key (local file:// source, or a remote model not yet fingerprinted).

Why

Follow-up from the #960 review: in these cases the pod silently fell back to an emptyDir and re-downloaded the model on every restart, with no event or condition. #960 already warned for the pvc://-source conflict; this covers the symmetric case.

Fixes #965

How

• The check mirrors the useCache gate in constructDeployment; it lives in a warnIgnoredModelCacheClaim helper next to the other claimName logic (extracted rather than inlined because the extra branches pushed Reconcile over the gocyclo limit). Event messages say why the claim was ignored and that the pod gets an ephemeral emptyDir.
• Envtest reconcile tests with a FakeRecorder assert every ModelCacheClaimIgnored variant — including the pre-existing pvc:// case, which was previously unasserted — plus a no-warning case when caching is active.
• docs/MODEL-CACHE.md: updated the ignored-claim bullet and added a note that claimName is mutable and the old claim is not garbage-collected.
• Skipped the ModelCachePVCNotFound condition-reason nice-to-have: the Degraded reason is hardcoded in the shared updateStatusWithSchedulingInfo switch, so a specific reason means plumbing a new parameter through it — happy to do as a separate PR if wanted.

AI assistance: authored by Claude (Fable 5) operating under the maintainer's direction; reviewed before submitting.

Checklist

• Tests added/updated
• make test passes locally (go test ./internal/controller/... with envtest assets, 506/506)
• make lint passes locally (golangci-lint run ./internal/... ./api/..., 0 issues)
• Commit messages follow conventional commits
• All commits are signed off (git commit -s) per DCO
• AI assistance (if any) is disclosed above, per CONTRIBUTING.md
• Documentation updated (if user-facing change)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[Defilan]

Review

Approve. This closes the silent-drop gap I flagged on #960 (filed as #965): when spec.modelCache.claimName is set but caching is off, the user now gets a ModelCacheClaimIgnored warning instead of a silent emptyDir.

Verified:

• warnIgnoredModelCacheClaim fires the existing ModelCacheClaimIgnored reason across all three ignore cases (pvc:// source, ModelCachePath == "", empty cache key). The switch conditions are the exact negation of the real useCache gate (effectiveModelCacheKey(model) != "" && r.ModelCachePath != ""), so the warning mirrors the actual storage path chosen.
• Wired unconditionally in Reconcile before reconcileDeployment (not dead code), and it back-fills the previously-inline pvc:// warning.
• No false positive on the happy path (claimName set + caching on), asserted by a dedicated NotTo(ContainElement(...)) test; the envtest covers all four cases with a FakeRecorder.
• Tightly scoped (helper extraction + call-site swap + tests + a docs bullet), DCO signed.

One cosmetic note: the test/doc reference #928 rather than the silent-drop follow-up #965 this resolves; I'll close #965 pointing here.

Thanks for picking this up.