fix!: preserve feature traces when owner lookup is unavailable (#8368)

* fix!: preserve feature traces when owner lookup is unavailable

* test: strengthen feature trace cancellation assertions

* fix: preserve feature trace provider readiness errors

* test: verify all feature trace reference sources

* test: verify IDA guidance at its owning boundary

* style: format feature trace regression

docs/mcp-contracts.md

@@ -210,8 +210,13 @@ unresolved relationship reads. Cancellation remains a tool error.
 
 `trace_feature` validates each reference's containing-procedure resolution using
 the same contract as navigation context. Explicit absence remains a successful
-negative observation; malformed provider replies return `unreadable_output`
-for `resolve_containing_procedure` before successful-result projection.
+negative observation. If the provider reports a non-retryable capability refusal
+attributed to the owner lookup without incomplete cleanup, the reference remains visible
+with `containing_procedure.status: "unavailable"` and a residual unknown. That
+unknown does not imply references were truncated.
+Malformed provider replies return `unreadable_output` for
+`resolve_containing_procedure` before successful-result projection;
+cancellation and incomplete cleanup remain errors.
 
 REA prepares complete MCP results within the pinned stdio client's 10 MiB
 receive-buffer budget, including both text and structured representations and