fix(quarantine): expose output schema in tool diff endpoint (MCP-2085)#638
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The tool-quarantine change-detection hash covers description, input schema,
and output schema, but GET /api/v1/servers/{id}/tools/{tool}/diff only
returned the description and input schema. When an upstream evolved only its
output schema (e.g. Google sqladmin adding a "POSTGRES_20" enum value), the
visible description was byte-identical, so the flagged tool looked like a
phantom rug-pull false positive.
Add previous_output_schema / current_output_schema (already stored on the
ToolApprovalRecord) to the diff response so an operator can see exactly what
changed before approving. Document the field in docs/api/rest-api.md and add
a regression test for an output-schema-only change.
Note: change-detection itself is correct — the upstream schema genuinely
changed. This deliberately does NOT weaken the rug-pull hash (no
auto-approval of additive enum widenings); the fix is transparency, not
relaxing security.
Related #634
Related MCP-2085
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…UI (#639) The tool-quarantine approval UI flagged a tool as "changed" whenever its description, input schema, OR output schema hash differed from the approved version, but rendered only the description diff. A schema-only change was therefore an invisible phantom diff — the operator saw a "changed" badge with no visible reason. Render up to three labeled before/after sections (Description, Input Schema, Output Schema), each shown only when that field actually changed, consuming the previous_output_schema / current_output_schema fields the diff endpoint now exposes (PR #638). Schema bodies are pretty-printed before the word-diff so additive changes (e.g. a new enum value) read clearly. Backend keeps rug-pull detection strict; this change is transparency only. Diff-section selection is extracted into computeToolDiffSections (utils/toolDiff) with a vitest covering the output-schema-only case. Related MCP-2096, MCP-2085
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Summary
Fixes the backend half of MCP-2085. The tool-quarantine change-detection hash covers
description + inputSchema + outputSchema(internal/runtime/tool_quarantine.go), butGET /api/v1/servers/{id}/tools/{tool}/diffonly returnedprevious_description/current_descriptionandprevious_schema/current_schema. It omitted the output-schema fields entirely, even though they already exist onToolApprovalRecordand are part of the hash.Consequence: when an upstream evolves only its output schema — e.g. Google
sqladminadding"POSTGRES_20"to a database-version enum — the description and input schema stay byte-identical, so the diff the operator sees is empty. Thechangedflag then reads as a phantom rug-pull false positive and erodes trust in the feature.Change
internal/httpapi/server.go—handleGetToolDiffnow also returnsprevious_output_schema/current_output_schema.docs/api/rest-api.md— document the two new response fields.internal/httpapi/tool_quarantine_test.go— regression testTestHandleGetToolDiff_OutputSchemaOnlyChange(thecreate_backupcase: identical desc + input schema, output schema gainsPOSTGRES_20), plus assertions on the existing test that input-schema fields are surfaced.Design decision (Part 1 of the issue)
The issue offered options including auto-approving "additive enum widenings". I deliberately did not weaken the rug-pull hash:
POSTGRES_20enum)", the operator can approve in one click with full context.So the backend fix is transparency, not relaxing security.
Out of scope (delegated)
The frontend rendering half —
frontend/src/views/ServerDetail.vueshowing three diff sections (Description / Input Schema / Output Schema) and the option-(b) batch "schema updated on N tools" review — is a separate lane and tracked as a child issue for the Frontend engineer. This PR is the enabling backend change it depends on.Verification
go test ./internal/httpapi/ -race✅go test ./internal/runtime/ -run TestCalculateToolApprovalHash_Stability✅ (hash canary unchanged)go build ./cmd/mcpproxy✅./scripts/run-linter.sh→ 0 issues ✅Related #634
Related MCP-2085