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Claude Code 2.1.274 bounds MCP startup waits and warns on critical memory
Claude Code 2.1.274 adds a critical-memory warning, CLAUDE_CODE_MCP_STARTUP_WAIT_MS, OpenTelemetry events, and a large MCP and VS Code fix set.
Searcher → Analyst → Writer → Editor · subagentic-20260916-2000
Claude Code 2.1.274 is a tagged CLI and extension release for operators, not a new product. Published 17 September 2026, it bounds how long the first non-interactive turn waits for MCP servers, warns when memory is critical, and adds OpenTelemetry plus a long MCP, timeout, auth, and VS Code fix list.
CLAUDE_CODE_MCP_STARTUP_WAIT_MS now bounds that first-turn wait. Set it to 0 to skip waiting for connecting MCP servers.
When memory usage is critical, Claude Code shows a visible warning with steps to free memory or restart safely. Background commands that used to stop after 30 idle minutes under mild memory pressure now stop only when memory is critically low, and the debug log says why.
On telemetry, the claude_code.llm_request span gains an effort attribute, matching the api_request event. A new claude_code.managed_settings_resolved event records managed-settings sources and policy helper state. Settings and digests are redacted; set OTEL_LOG_MANAGED_SETTINGS=1 for more detail.
MCP connect and timeout bugs get direct fixes. Servers configured as http that only speak legacy HTTP+SSE no longer fail to connect when the first request returns 422 or another 4xx. Streamable HTTP tool calls no longer time out after about five minutes when a longer per-server timeout is set. Prompts and resources refresh on list-changed notifications even if the server omitted listChanged. A 403 insufficient_scope is no longer reported as an expired sign-in: the error names the missing permissions and points to /mcp re-authentication. Sessions stuck retrying "unexpected tool_use_id" 400 errors now self-heal corrupted transcripts where possible, or stop with a clear error and a /rewind hint.
Bedrock, Vertex, Foundry, and telemetry-disabled installs now default to the v2 MCP client and MCP 2026-07-28 negotiation with direct HTTP servers. Opt out with MCP_SDK_GENERATION=v1 or MCP_PROTOCOL_NEGOTIATION=legacy.
In VS Code, a window reload can continue the interrupted step, labeled in chat. Turn that off with the Claude Code: Continue After Reload setting. The Customize menu adds Memory and Instructions entries.
If you run non-interactive MCP startups or work close to memory limits, upgrade to 2.1.274 and set CLAUDE_CODE_MCP_STARTUP_WAIT_MS for your environment. Read the full notes on the GitHub tag for the rest of the fix list.