[dependabot]

Bumps fastmcp from 3.4.4 to 4.1.1.

Release notes

Sourced from fastmcp's releases.

v4.1.1: Regex Marks the Spot

Regex tool search now rejects patterns over 1,000 characters and stops after about a second, and SkillsDirectoryProvider discovers skill folders that are links again, including links to folders outside the skills root; a skill's own files must still resolve inside the folder it links to. All 4.x users are encouraged to upgrade. Thanks to our 4 contributors, including 1 first-time contributor.

What's Changed

Security 🔒

• Keep linked skill folders discoverable by @​zzstoatzz in PrefectHQ/fastmcp#5766
• Bound regex tool search by pattern length and time by @​zzstoatzz and @​SAYUTIM in PrefectHQ/fastmcp#5771

Fixes 🐞

• Keep an unparseable proxy setting from aborting the update check by @​zzstoatzz and @​ker2xu in PrefectHQ/fastmcp#5639
• Keep the JWKS refresh lock clear of subclass attributes by @​zzstoatzz in PrefectHQ/fastmcp#5770

Examples & Contrib 💡

• fix: convert version query param to VersionSpec in component manager routes by @​BlueX888 in PrefectHQ/fastmcp#5575

New Contributors

• @​ker2xu made their first contribution in PrefectHQ/fastmcp#5639

Full Changelog: PrefectHQ/fastmcp@v4.1.0...v4.1.1

v4.1.0: Fourth and One

FastMCP 4.1.0 is a maintenance release at heart: a broad sweep of fixes across OpenAPI, proxies, auth, tasks, and the CLI, plus full Python 3.15 support. It doesn't change how most servers behave. A few security fixes do tighten inputs that FastMCP previously accepted, though, and our versioning policy keeps breaking changes out of patch releases, so this ships as a point-one release.

Check these before upgrading:

• MultiAuth now qualifies client IDs by source, so existing MultiAuth sessions and tasks start new ownership scopes. Finish pending tasks before upgrading.
• Regex tool search uses Pydantic's regex engine, which doesn't support lookarounds or backreferences.
• Skill files must resolve inside their configured directories.
• OpenAPI path parameters reject . and .. segments.
• HTTP sessions now expire after the MCP SDK's 30-minute idle default instead of never.
• CodeMode requires Monty 1.1, which renames max_duration_secs to max_feed_duration_secs.

Thanks to our 48 contributors, including 21 first-time contributors!

What's Changed

Breaking Changes ⚠️

• fix(http): preserve the SDK's default session idle timeout by @​asts-top in PrefectHQ/fastmcp#5229
• Restore full Python 3.15 support by @​Kludex in PrefectHQ/fastmcp#5558

Enhancements ✨

• enhancement: Configure token introspection audiences by @​jlowin and @​sajdakabir in PrefectHQ/fastmcp#5461
• fix: Make proxy HTTP header forwarding configurable by @​jlowin in PrefectHQ/fastmcp#5462
• enhancement: Configure upload retention in memory by @​jlowin and @​warlocksmurf in PrefectHQ/fastmcp#5463
• Clarify maintainer review decisions by @​jlowin in PrefectHQ/fastmcp#5466
• feat: persist encrypted CLI OAuth tokens by @​andreivince in PrefectHQ/fastmcp#5405
• feat(auth): add TokenCache support to GoogleTokenVerifier and GoogleProvider by @​jerive in PrefectHQ/fastmcp#5366
• Add gitleaks secret scanning to prek by @​strawgate in PrefectHQ/fastmcp#5355
• Keep review design decisions with maintainers by @​jlowin in PrefectHQ/fastmcp#5468

... (truncated)

Changelog

Sourced from fastmcp's changelog.

---

title: "Changelog" icon: "list-check" rss: true tag: NEW

v4.1.3: Root Awakening

This release updates certifi-backed dependencies following the eMudhra CA compromise and fixes public-client OAuth authentication, empty visibility selections, generator transforms, and per-server timeouts for ordinary requests. FastMCP 4 uses system trust by default: follow the security notice to update operating-system, container, custom, and installer trust stores; upgrading FastMCP alone is insufficient. Thanks to our 11 contributors, including 6 first-time contributors.

Security 🔒

• Require certifi 2026.10.19 or later for certifi-backed server dependencies and optional SDK integrations, and document system, custom, and installer trust-store updates by @​zzstoatzz in #5945.

Enhancements ✨

• Chart public backlog counts and closure outcomes by @​zzstoatzz in #5942

Fixes 🐞

• Default the upstream token auth method to none without a client secret by @​asasemahmed in #5879
• fix: preserve empty session visibility selections by @​himanshuchawla0807-gif in #5944
• test(mount): make unreachable proxy failures deterministic by @​CharlesYXW and @​ch-z-hc in #5584
• fix(tools): materialize generator transform_fn results in TransformedTool.run by @​BlueX888 and @​nandanadileep in #5672
• Honor per-server MCP config timeouts by @​atty57, @​phnmn, and @​CRYPTONIKAV in #5758
• fix: don't classify a tool body's own TimeoutError as the tool timeout by @​Wilson0511 in #5940

New Contributors

• @​phnmn made their first contribution in #5758
• @​CRYPTONIKAV made their first contribution in #5758
• @​himanshuchawla0807-gif made their first contribution in #5944
• @​CharlesYXW made their first contribution in #5584
• @​atty57 made their first contribution in #5758
• @​Wilson0511 made their first contribution in #5940

Full Changelog: v4.1.2...v4.1.3

v4.1.2: License to Deny

Component authorization now applies after transforms, denied resources cannot fall through matching templates, and OAuth client credentials providers support issuer binding across fresh and cached-token flows. Existing configurations remain compatible, but users of ClientCredentialsOAuthProvider or PrivateKeyJWTOAuthProvider must set issuer to enable this protection; upgrading alone is insufficient. Thanks to our 18 contributors, including 9 first-time contributors.

Security 🔒

• Authorize transformed components and prevent denied-resource template fallback by @​zzstoatzz and @​rishid in #5933
• Bind OAuth client credentials to a configured issuer, including cached-token renewal, by @​zzstoatzz and @​LHMisme420 in #5933

Enhancements ✨

• Add SEP-2640 Skills extension foundation by @​strawgate in #5057
• Write down triage and merge norms in docs/development by @​zzstoatzz in #5872
• Add experimental Skills discovery to SkillsDirectoryProvider by @​zzstoatzz in #5704

... (truncated)

Commits

• 7f3c53e docs: add v4.1.1 changelog entries (#5796)
• fb52bd3 Bound regex tool search by pattern length and time (#5771)
• 307aa56 Keep the JWKS refresh lock clear of subclass attributes (#5770)
• 564d8b6 Keep linked skill folders discoverable (#5766)
• e2fcc41 Keep an unparseable proxy setting from aborting the update check (#5639)
• 9c4a0b9 Convert the component manager's version query param to a VersionSpec (#5575)
• 51b618f Merge pull request #5635 from PrefectHQ/docs/changelog-4.1.0
• e8327ee docs: structure v4.1.0 release notes
• d7186ba docs: exclaim v4.1.0 contributor thanks
• d87d171 docs: add v4.1.0 changelog entries
• Additional commits viewable in compare view

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