fix(mcp): guardrail authorize fails CLOSED by default#78
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The MCP guardrail (#14) called /api/mcp/authorize and, on any error, returned null which guardrailBlockResult treated as 'allow' — a down or unreachable AgentGate silently waved every tool call through (same fail-open class as the agentgate-ucp C1 audit finding). Now an authorize error yields an 'error' verdict that blocks the call. Opt back into the old behavior with AGENTGATE_GUARDRAIL_FAIL_OPEN=1 for deployments where the guardrail is advisory. Tests updated + added. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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The AgentGate MCP guardrail (#14) failed open:
authorizeToolreturnednullon any error from/api/mcp/authorize, andguardrailBlockResult(null)treated that as allow — so a down/unreachable AgentGate silently passed every tool call. Same class as the agentgate-ucp C1 red-team finding.errorverdict →guardrailBlockResultblocks the call (isError).AGENTGATE_GUARDRAIL_FAIL_OPEN=1restores fail-open for advisory deployments.🤖 Generated with Claude Code