* fix(mcp): preserve server binding history across gateway workers
A peer Gateway worker could keep a stale pooled session after another worker deleted and identically re-added a stdio server, because the final effective MCP slice matched the revision it had already applied.
Record a per-server lifecycle generation in the shared extensions config and consume it in the reader, discovery claim, and committed handoff so an observed generation change force-rebinds only the affected server. Legacy configs derive a stable in-memory token; deletions leave permanent tombstones.
* fix(mcp): fail closed on an invalid mcpLifecycle instead of retrying
An unverifiable mcpLifecycle made initialize_mcp_tools() unpublishable, so get_cached_mcp_tools() retried discovery forever and could keep respawning stdio servers. Abort discovery on an invalid ledger after conservatively retiring local MCP state; a fixed config recovers on the next call.
Also documents the rolling-upgrade prerequisite: cross-worker ABA detection requires configuration writes to go through a lifecycle-aware writer.
* refactor(mcp): share stdio fingerprinting across lifecycle paths
Reuse lifecycle._stdio_fingerprints from the applied-revision builder so the connection-identity rule has a single implementation, and move the unusable-server diagnostic into the shared helper.
Add a regression proving the Gateway Skills writer preserves mcpLifecycle byte-for-value, and document that DeerFlowClient.update_mcp_config can raise RuntimeError after the config was committed.
* docs(mcp): condense lifecycle guidance under the AGENTS chain limit
The effective mcp/AGENTS.md chain was 15 bytes under the 98,304-byte CI hard limit, so the standalone cross-worker lifecycle bullet pushed it over. Fold the mcpLifecycle and rolling-upgrade facts into the existing selective-reconciliation bullet and condense it, keeping the chain under the limit while preserving the contract.
* docs: trim inherited agent guidance below CI size limit
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Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
