fix(mcp): v0.0.95 compat shims for gradual rollout#1099
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mattzcarey wants to merge 6 commits intomainfrom
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fix(mcp): v0.0.95 compat shims for gradual rollout#1099mattzcarey wants to merge 6 commits intomainfrom
mattzcarey wants to merge 6 commits intomainfrom
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During gradual rollouts, old Workers (v0.0.95) and new DOs (v0.7.5+) must interoperate. The RPC interface changed completely between versions: - _init/isInitialized/setInitialized → updateProps/getInitializeRequest/setInitializeRequest - WS upgrade to /streamable-http → cf-mcp-method/cf-mcp-message headers - Raw JSONRPC responses → CF_MCP_AGENT_EVENT wrappers DO-side (index.ts): - Add _init(), isInitialized(), setInitialized() compat shims - Dual storage: setInitializeRequest also writes "initialized" boolean - fetch() override detects /streamable-http path, caches transport type - Deferred onStart: tolerate transport init failure for old Workers - onMessage handler for legacy ws.send() frames - shouldSendProtocolMessages suppresses for old-style connections - getTransportType/getSessionId fall back for names without prefix - Tag new-style connections with _mcpNewStyle in onConnect Worker-side (utils.ts): - readInitializedState/writeInitializedState with isRpcMethodMissing fallback - ws.send() messages after connect for old DOs that ignore headers - Handle both CF_MCP_AGENT_EVENT and raw JSONRPC response formats Transport (transport.ts): - writeSSEEvent sends raw JSONRPC for old Workers (no _mcpNewStyle) - Preserve connection state when setting requestIds/_standaloneSse Tests: - 8 compat tests simulating old Worker control flow against new DO
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oxlint in CI rejects `any` — use `as unknown as OldWorkerStub` instead.
Old Worker uses `idFromName("streamable-http:${sessionId}")`, not a
plain session ID. Updated test to match actual v0.0.95 behavior.
Old Workers use idFromName("streamable-http:${sessionId}"), so the name
always has the transport prefix. Remove _cachedTransportType, deferred
onStart, lazy transport init, transportType storage, and plain-name
fallbacks that were added for a case that doesn't occur.
agents
@cloudflare/ai-chat
@cloudflare/codemode
hono-agents
@cloudflare/voice
@cloudflare/worker-bundler
commit: |
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Summary
Adds backwards/forwards compatibility between v0.0.95 Workers and v0.7.5+ DOs for the streamable-http transport, enabling gradual rollouts where both versions run simultaneously.
_init(),isInitialized(),setInitialized()methods that v0.0.95 Workers call via RPC; dual storage so both old and new formats workreadInitializedState/writeInitializedStatehelpers that try new RPC methods first, fall back to old on method-missing errors;ws.send()after connect for old DOs that ignore headers; handles bothCF_MCP_AGENT_EVENTand raw JSONRPC response formatswriteSSEEventsends raw JSONRPC for old Workers (detected via_mcpNewStyleconnection tag), wrappedCF_MCP_AGENT_EVENTfor newonStarttolerates transport init failure;fetch()andonMessage()lazily initialize when transport type becomes known_init,/streamable-httpWS upgrade,ws.send()messages, raw JSONRPC responses)Context
A customer upgrading from v0.0.95 → v0.7.5 uses gradual rollouts. During deployment, old Workers call new DOs (and vice versa). The RPC interface changed completely between versions — this PR bridges both directions for streamable-http transport.
Test plan
npm run build— compiles cleannpm run check— format/lint/types passnpm test— all 994 tests pass (52 files, 8 skipped pre-existing)