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Cherry-pick: perf: faster cold start and less memory after startup (#919 to #925, #932) - #931
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frontegg-david merged 8 commits intoOct 21, 2026
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The title clearly identifies the cherry-pick and its main performance goals: faster cold starts and lower memory use. |
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The description explains the purpose, lists the included changes and conflicts, reports benchmark results, and documents tests. It does not use the template headings exactly, but it provides the requi… |
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Review comments at @libs/sdk/src/transport/transport.registry.ts:
- Line 1103: Apply the existing creationMutex pattern to both stateless
transport creation methods, covering the lookup, asynchronous transporter
loading, ready() call, and insertLocal(key, transporter) so creation is
serialized per key. Preserve the existing disposal callbacks and ensure
concurrent requests reuse the single inserted transporter.
Review comments at @scripts/escape-non-ascii.mjs:
- Line 30: Update the comparison around compiledProgram so equivalent
regular-expression literals with non-ASCII characters, such as /é/ and /\u00e9/,
are accepted after escapeNonAscii processing. Use a validation approach that
compares regex semantics separately or otherwise recognizes equivalent literals,
while preserving rejection of genuinely changed program behavior.
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⛔ Files ignored due to path filters: 1
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Performance Test ResultsStatus: ✅ All tests passed Summary
Total: 101 tests across 21 projects 📊 View full report in workflow run Generated at: 2026-10-21T14:10:16.274Z |
…e per character (#919) V8 keeps the source of every loaded script for the life of the process, and stores it with two bytes per character when one character is above U+00FF. esbuild escapes non-ASCII characters in strings and identifiers but copies the comments it keeps as they are, so an em dash or a box-drawing rule in a comment doubled the memory the SDK bundle's source takes (6 MB instead of 3 MB); tsc output (the CLI, @frontmcp/nx) keeps them in strings too. Each publishable package's build now ends with scripts/escape-non-ascii.mjs, which rewrites every non-ASCII character in its .js, .mjs and .cjs output as a \uXXXX escape. A file is rewritten only when esbuild compiles the escaped text to the same program as the original, so a raw template string or a character after a backslash stops the build instead. CI checks the built output with --check. (cherry picked from commit 12cfece)
…nder require() (#920) * perf(protocol): load the MCP client and its transports on first use under require() @frontmcp/protocol's root re-exported the MCP SDK's Client, StreamableHTTPClientTransport, SSEClientTransport and StdioClientTransport, so every CommonJS server loaded the SDK's client, its OAuth client, the SSE and streamable HTTP client transports, eventsource and cross-spawn (31 files) at startup, though a server only uses them for remote apps. The client exports now come from a #client subpath import. Under the require condition it resolves to lazy-client.js, whose getters load each MCP SDK module the first time the export is read; worker, browser and ESM importers get the same static re-exports as before (an ESM importer gets esm/client.mjs, which strip-dist now maps for an `import` target, so the client still comes from the MCP SDK's ESM build). The public exports don't change. * test(protocol): cover the package's exports, now that it has tests and so a coverage threshold lazy-client.spec.ts is @frontmcp/protocol's first test file, so CI's protocol:test --coverage now applies the package's 95% threshold, and the re-export modules nobody had tested left it at 21%. exports.spec.ts checks that the Node modules hand back the MCP SDK's classes, that the browser stand-ins throw their errors, and the 2026-07-28 version helpers. index.ts is left out of coverage, as in most of the libraries here. (cherry picked from commit 0f7c402)
…h loads none of the parser (#921) @frontmcp/utils imported analyzeForReDoS and REDOS_THRESHOLDS from the @enclave-vm/ast root, which loads the whole AST validator and its parser (acorn, acorn-walk, astring), so every FrontMCP server loaded them at startup. @enclave-vm/ast 2.17.0 exports the analyzer alone as @enclave-vm/ast/redos (agentfront/enclave#104). @enclave-vm/core moves to 2.17.0 with it in the root and plugin-codecall, since core pins ast exactly; the tree keeps one @enclave-vm/ast. (cherry picked from commit 0ac0461)
…no source maps (#922) * perf(build): publish whitespace-minified CommonJS and ESM builds and no source maps V8 keeps the source of every loaded script for the life of the process, and parses all of it at load. The SDK's CommonJS bundle was 3.07 million characters, of which comments and indentation are about a third. Every package's build-cjs and build-esm now set esbuild's minifyWhitespace: comments and whitespace go, identifiers and syntax stay. The SDK's index.js drops from 3.07 MB to 2.0 MB. The tsc-built packages (frontmcp, @frontmcp/nx, @frontmcp/skills) stop emitting .js.map files, so no package ships source maps. minifyWhitespace also drops the comments bundlers read. The one that changes behavior is the webpackIgnore / @vite-ignore pair on the ESM loader's import() of a computed specifier: without it, rspack (the CLI's lambda and vercel bundler) replaces the import with a context that throws "Cannot find module". That function now lives in its own module, reached through the #import-computed subpath import and built unminified, so the comments stay. The browser builds (dist/browser) are not minified, so the @__PURE__ annotations their per-module tree-shaking relies on stay too. * perf(build): keep the browser-facing packages unminified, so bundlers keep their pure annotations esbuild's minifyWhitespace drops /* @__PURE__ */ annotations, which bundlers use to tree-shake @frontmcp/react, @frontmcp/ui and @frontmcp/plugin-webmcp out of browser apps. Servers don't load those packages for their own startup, so minifying them saved nothing this stack measures. (cherry picked from commit 86bccf8)
…oaded (#923) runStdio() took McpServer and StdioServerTransport from `await import('@frontmcp/protocol')`. In a CommonJS process that import resolves the package's `import` condition, so a stdio server loaded a second, ESM copy of @frontmcp/protocol and, through it, of the MCP SDK (types.js and its zod schemas, the client, shared/protocol.js, zod-to-json-schema), on top of the CommonJS copy the SDK had already required. runStdio() now uses the statically imported @frontmcp/protocol, as the HTTP transport already does, so a CommonJS stdio server uses one copy of the MCP SDK. In an ESM process the import resolves the same ESM module as before. (cherry picked from commit 9201f8a)
…e first HTTP session (#924) * perf(sdk,protocol): load the Streamable HTTP server transport with the first HTTP session A stdio server loaded the MCP SDK's Node Streamable HTTP transport at startup, and with it @hono/node-server, which reads the global Request and Response when it loads and so makes Node load its bundled undici. Two things did it: @frontmcp/protocol's CommonJS root required #mcp-streamable-http, and the SDK's RecreateableStreamableHTTPServerTransport, which extends the MCP SDK class, was defined when the SDK's root initialized the transport barrel. - #mcp-streamable-http gets a require variant whose getters load each transport the first time it is read, and a types entry ahead of it. - TransportStreamableHttpAdapter imports the recreateable transport as a type and loads it with loadStreamableHttpTransport(); TransportService awaits it where it creates a LocalTransporter, which it already did asynchronously. - The SDK root imports the in-memory server, web-fetch handler, web-standard helpers and transport types from their modules instead of the barrel, which initialized every module transport/index.ts re-exports. An HTTP server now loads the transport with its first session; a stdio server never does. * perf(sdk): load the Streamable HTTP transport only for Streamable HTTP and stateless HTTP sessions An SSE session uses TransportSSEAdapter, which never touches the Streamable HTTP class, so an SSE-only server no longer loads it either. (cherry picked from commit 4129311)
semver.utils.ts imported the semver package root, which loads all 46 of its files, at startup. It uses seven functions; importing them from their own modules (semver/functions/*.js, semver/ranges/*.js) loads 23 files, with the same results. (cherry picked from commit f9bf70c)
…its key arrive together (#932) * fix(sdk): create one stateless transport when the first requests for its key arrive together getOrCreateAnonymousStatelessTransport and getOrCreateAuthenticatedStatelessTransport checked lookupLocal(key), then awaited the transport's creation and ready() before insertLocal(key). Concurrent first requests could each create one; the later insert replaced the earlier, and the earlier one's disposal then evicted the replacement by key. Both now go through the creationMutex createTransporter already uses. (cherry picked from commit 21c4da8) * build(scripts): say why escape-non-ascii stops on a regular-expression literal or tagged template, and how to fix it esbuild keeps non-ASCII characters in regular-expression literals and tagged templates as written, so it can't confirm that an escape there leaves the program the same, and after a backslash an escape doesn't. The script still stops the build, now naming both cases and the fix: write the character as a \\uXXXX escape in the source. (cherry picked from commit 998f5d5) * build(scripts): tell how to write a tagged template without non-ASCII, since an escape changes its raw text A tag that reads raw text, like String.raw, gets the escape's backslash and letters, so the advice to write \uXXXX escapes only holds for regular-expression literals. For a tagged template the error now says to write it without them, for example with an interpolation under String.raw. (cherry picked from commit 26a3aab)
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Cherry-pick to main
This PR brings everything merged to
release/1.10.xsince #914 tomain, as one PR: #919 to #925 (the cold start and memory round) and #932 (the fixes from this PR's own review). Each release squash commit is picked in order withgit cherry-pick -x, so every commit names its source onrelease/1.10.x. It replaces the per-PR cherry-picks the workflow opened: #928 and #929, and issues #930 and #933.release/1.10.x12cfeceda0f7c4025c@frontmcp/protocolloads the MCP client and its transports on first use underrequire().0ac04611a@frontmcp/utilstakes the ReDoS analyzer from@enclave-vm/ast/redos(agentfront/enclave#104), which loads none of the parser.86bccf830react,uiandplugin-webmcpstay unminified.9201f8a9441293117ff9bf70ce626a3aabadcreateTransporter'screationMutex).escape-non-asciisays why it stops on a regular-expression literal or tagged template, and how to write each without non-ASCII.Every other change on
release/1.10.xis already onmain, apart from the version bumps:main.Conflicts
plugins/plugin-codecall/package.json(from perf(utils): take the ReDoS analyzer from @enclave-vm/ast/redos, which loads none of the parser #921):@enclave-vm/astand@enclave-vm/coretake perf(utils): take the ReDoS analyzer from @enclave-vm/ast/redos, which loads none of the parser #921's^2.17.0;@frontmcp/protocolkeepsmain's1.10.8.yarn.lock: regenerated withyarn installfrommain's lockfile.yarn why @enclave-vm/astshows one version, 2.17.0.Nothing else conflicted.
Results
FrontMCP 1.10.9-rc.2, which has #919 to #925, against rc.1 and 1.10.7, measured in one session with the benchmark's harness. The load average was 3.4 to 4.0 during cold start; it was higher during throughput, which ran under the same conditions for all three.
Tests
4567a1589), which had the three fix(sdk): create one stateless transport when the first requests for its key arrive together #932 commits picked separately. On that head:node --test scripts/*.test.mjs: 83 pass;nx run-many -t test --coverage --projects=protocol,utils: pass;transport,esm-loaderandfront-mcpsuites: 1,410 tests pass;typecheckandlintforprotocol,utils,sdkandplugin-codecall: pass.escape-non-ascii.test.mjspasses (5 tests).