build(deps): bump werkzeug from 3.1.6 to 3.1.9 in /backend

[dependabot]

Bumps werkzeug from 3.1.6 to 3.1.9.

Release notes

Sourced from werkzeug's releases.

3.1.9

This is the Werkzeug 3.1.9 security fix release, which fixes security issues and bugs but does not otherwise change behavior and should not result in breaking changes compared to the latest feature release.

PyPI: https://pypi.org/project/Werkzeug/3.1.9/ Changes: https://werkzeug.palletsprojects.com/page/changes/#version-3-1-9 Milestone: https://github.com/pallets/werkzeug/milestone/46?closed=1

• safe_join on Windows does not allow special devices names with empty ADS markers on NTFS. GHSA-g6x2-hccm-hh4m
• ProfilerMiddleware uses profiling.tracing on Python 3.15. #3207
• uri_to_iri and iri_to_uri preserve empty username, password, and port 0. #3189
• Improve performance of parse_options_header. #3231
• Improve performance of parse_etags. #3231
• Improve performance of parse_cookie. #3231
• get_host also checks that the port is in the valid range. #3236
• The int URL converter returns a 404 instead of 500 error when the value is longer than sys.get_int_max_str_digits(). #3237
• Improve debugger PIN generation from cgroup data inside Podman. #3245
• Authorization parsing basic auth disallows non-base64 characters. #3248
• application/x-www-form-urlencoded form data is no longer limited to max_form_memory_size, only max_content_length. #3251
• LimitedStream.readinto does not resize the buffer when it reads less than the remaining size. #3253
• Rules with 10 or more converters in a single part assign matched values correctly. #3254
• The invalid Range suffix length -0 is no longer accepted. #3255

3.1.8

This is the Werkzeug 3.1.8 fix release, which fixes bugs but does not otherwise change behavior and should not result in breaking changes compared to the latest feature release.

PyPI: https://pypi.org/project/Werkzeug/3.1.8/ Changes: https://werkzeug.palletsprojects.com/page/changes/#version-3-1-8 Milestone: https://github.com/pallets/werkzeug/milestone/45?closed=1

• Request.host and get_host return the empty string if the header is missing or has invalid characters. #3142

3.1.7

This is the Werkzeug 3.1.7 fix release, which fixes bugs but does not otherwise change behavior and should not result in breaking changes compared to the latest feature release.

PyPI: https://pypi.org/project/Werkzeug/3.1.7/ Changes: https://werkzeug.palletsprojects.com/page/changes/#version-3-1-7 Milestone: https://github.com/pallets/werkzeug/milestone/44?closed=1

• parse_list_header preserves partially quoted items, discards empty items, and returns empty for unclosed quoted values. #3128
• WWWAuthenticate.to_header does not produce a trailing space when there are no parameters. #3127
• Transfer-Encoding is parsed as a set. #3134
• Request.host, get_host, and host_is_trusted validate the characters of the value. An empty value is no longer allowed. A Unix socket server address is ignored. The trusted_list argument to host_is_trusted is optional. #3113
• Fix multipart form parser handling of newline at boundary. #3088
• Response.make_conditional sets the Accept-Ranges header even if it is not a satisfiable range request. #3108
• merge_slashes merges any number of consecutive slashes. #3121

Changelog

Sourced from werkzeug's changelog.

Version 3.1.9

Released 2026-09-27

• safe_join on Windows does not allow special devices names with empty ADS markers on NTFS. :ghsa:g6x2-hccm-hh4m
• ProfilerMiddleware uses profiling.tracing on Python 3.15. :issue:3207
• uri_to_iri and iri_to_uri preserve empty username, password, and port 0. :issue:3189
• Improve performance of parse_options_header. :pr:3231
• Improve performance of parse_etags. :pr:3231
• Improve performance of parse_cookie. :pr:3231
• get_host also checks that the port is in the valid range. :pr:3236
• The int URL converter returns a 404 instead of 500 error when the value is longer than sys.get_int_max_str_digits(). :issue:3237
• Improve debugger PIN generation from cgroup data inside Podman. :issue:3245
• Authorization parsing basic auth disallows non-base64 characters. :pr:3248
• application/x-www-form-urlencoded form data is no longer limited to max_form_memory_size, only max_content_length. :pr:3251
• LimitedStream.readinto does not resize the buffer when it reads less than the remaining size. :pr:3253
• Rules with 10 or more converters in a single part assign matched values correctly. :pr:3254
• The invalid Range suffix length -0 is no longer accepted. :pr:3255

Version 3.1.8

Released 2026-04-02

• Request.host and get_host return the empty string if the header is missing or has invalid characters. :issue:3142

Version 3.1.7

Released 2026-03-23

• parse_list_header preserves partially quoted items, discards empty items, and returns empty for unclosed quoted values. :pr:3128
• WWWAuthenticate.to_header does not produce a trailing space when there are no parameters. :issue:3127
• Transfer-Encoding is parsed as a set. :pr:3134
• Request.host, get_host, and host_is_trusted validate the

... (truncated)

Commits

• 6604c3b release version 3.1.9
• a78b30a update dependencies
• 8d77320 disallow special name with ads (#3309)
• b2a2c09 disallow special name with ads
• 4efac9d add links
• 400c23e Allow flit_core 4.x (#3261)
• 7132a19 allow flit_core 4
• 6fba87c only accept ASCII digits
• 263f5ca disallow range -0 (#3255)
• 0c419f9 disallow range -0
• Additional commits viewable in compare view

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High-level PR Summary

This PR updates the werkzeug dependency from version 3.1.6 to 3.1.9 in the backend requirements. The update includes important security fixes (particularly for safe_join on Windows and authorization parsing), along with performance improvements for header parsing functions and various bug fixes related to request handling, URL conversion, and form data processing.

⏱️ Estimated Review Time: 5-15 minutes

💡 Review Order Suggestion

Order	File Path
1	backend/requirements.txt

[ecc-tools]

ECC Tools / Security Evidence

Commit: 93752a84f90ea746fe49f4b337806d9bbf576498

Security evidence gate passed (success)

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Commit: 93752a84f90ea746fe49f4b337806d9bbf576498

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[ecc-tools]

ECC Tools / Reference Set Readiness

Commit: 93752a84f90ea746fe49f4b337806d9bbf576498

Reference set readiness gaps detected (neutral)

Reference evidence present for 0/7 areas (0%) across 1 changed file(s).

This check is based on files changed in this PR. Repository-level readiness is still reported by /ecc-tools analyze comments and generated manifests.

Area	Status	Evidence / Next Step
Deep analyzer corpus	Missing	Add analyzer fixture, golden, benchmark, or reference-set files that can catch analyzer regressions.
RAG/evaluator comparison	Missing	Add retrieval or evaluator reference-set comparison fixtures with expected ranking behavior.
PR salvage/review corpus	Missing	Add stale-PR, review-thread, reopen-flow, or salvage reference cases for queue cleanup automation.
Discussion triage corpus	Missing	Add public discussion triage fixtures, golden cases, or reference sets for informational, answered, and no-response classifications.
Harness compatibility	Missing	Add cross-harness, adapter-compliance, or harness-audit evidence for Claude, Codex, OpenCode, Zed, dmux, and agent surfaces.
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CI failure-mode evidence	Missing	Add captured CI failure logs, dry-run fixtures, or troubleshooting docs for common workflow failure modes.

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Commit: 93752a84f90ea746fe49f4b337806d9bbf576498

Hosted promotion readiness passed (success)

No hosted promotion evidence gaps detected across 1 changed file(s); 0 corpus scenarios had matching evidence.

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