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Engineering updates from the MCP Hangar team.

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The Layer Cake That Saved a 3 AM Incident

May 23, 2026 MCP Hangar Team

03:14:22 — a provider starts returning HTTP 200 responses with malformed payloads. Three seconds later, every agent call is succeeding through the backup. Nobody got paged. The interesting part is which layer did the work — and which layer was insurance the incident never needed.

mcp mcp-hangar reliability incidents observability architecture
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May 21, 2026 MCP Hangar Team

min_healthy Doesn't Fail Closed. It Labels.

Most teams read min_healthy as a quorum: drop below it, the group rejects. That's not what it does. The group keeps serving as long as one member is up. min_healthy is the threshold where the state label flips — and if you're not alerting on the label, the number is doing nothing.

mcp mcp-hangar reliability sla observability
May 19, 2026 MCP Hangar Team

Health Checks Lie. Circuit Breakers Tell the Truth.

Your MCP server passes every 30-second tools/list probe and fails 4 out of 5 real tool calls. The dashboard is green. The agent is producing garbage. Here's why the probe is the wrong instrument — and what the right one looks like.

mcp mcp-hangar reliability observability architecture
May 17, 2026 MCP Hangar Team

MCP Hangar Is Now Fully MIT

Everything in mcp-hangar is now MIT, effective v1.2.2. This release removes the dual-license model and simplifies the codebase for all users.

May 11, 2026 MCP Hangar Team

Tool Integrity for MCP: Digest Pinning in MCP Hangar v1.2

v1.2 introduces SHA-256 digest pinning for MCP tool schemas, implementing a preemptive version of SEP-1766 to detect drift and block unauthorized mutations.

May 11, 2026 MCP Hangar Team

SEP-1763 Compliance: How MCP Hangar Became an MCP-Native Interceptor

v1.2 implements SEP-1763 P1: hook-based event model, wildcard subscriptions, IMutator contract with priority-ordered pipeline, and interceptors/list endpoint.

May 10, 2026 MCP Hangar Team

MCP Hangar v1.1 -- Cost Attribution, Compliance Export, and End-to-End Caller Identity

v1.1 adds per-tool-call cost tracking, SIEM-ready compliance export (Splunk, Datadog, Sentinel), and end-to-end caller identity in every OTEL span.

April 17, 2026 MCP Hangar Team

MCP Hangar v1.0.1 -- Hardening After the April Audit

Security hardening release: SSRF protection, default-deny command allow-list, granular RBAC, WebSocket origin validation, and trusted proxy resolution.

April 13, 2026 MCP Hangar Team

Human-in-the-Loop for MCP: How the Approval Gate Works

Your LLM just decided to delete a production alert rule. You didn't ask it to. The approval gate puts a human between the decision and the execution — not for every tool call, but for the ones where 'undo' is a support ticket.

mcp mcp-hangar governance security llm enterprise human-in-the-loop
April 12, 2026 MCP Hangar Team

When Your LLM Won't Stop Talking: Rate Limiting in MCP Hangar

Your agent just discovered it can call hangar_call in a loop. Twelve hundred requests in ninety seconds. Here's how MCP Hangar's two-system rate limiting — token bucket at the command bus, exponential backoff on auth — puts a ceiling on that.

mcp mcp-hangar security observability architecture open-source
April 11, 2026 MCP Hangar Team

MCP Hangar v1.0 -- Production Release

MCP Hangar v1.0 ships identity propagation, compliance-grade audit, Kubernetes enforcement, and sub-millisecond proxy overhead.