diff --git a/.github/requirements/.pip-tools.toml b/.github/requirements/.pip-tools.toml
new file mode 100644
index 0000000..d64dd4b
--- /dev/null
+++ b/.github/requirements/.pip-tools.toml
@@ -0,0 +1,7 @@
+# Dependabot reads the legacy section; pip-tools reads the tool section.
+# setuptools is the required build backend, installed at a reviewed hash.
+[pip-tools]
+allow-unsafe = true
+
+[tool.pip-tools]
+allow-unsafe = true
diff --git a/.github/requirements/integration.in b/.github/requirements/integration.in
index 4a66d5c..cf7c349 100644
--- a/.github/requirements/integration.in
+++ b/.github/requirements/integration.in
@@ -1,6 +1,6 @@
 # Python 3.12 integration dependencies, locked for all runner platforms.
 # Regenerate: uv pip compile --universal --python-version 3.12 --generate-hashes
-# --only-binary :all: --exclude-newer 2026-10-02T00:00:00Z
+# --only-binary :all: --exclude-newer 2026-10-05T00:00:00Z
 # .github/requirements/integration.in -o .github/requirements/integration.txt
 setuptools>=77
 wheel
@@ -12,11 +12,12 @@ prometheus_client>=0.26.0
 defusedxml>=0.7.1
 je_action_core>=0.0.2
 PyYAML>=6.0.3
-tzdata>=2024.1; platform_system == 'Windows'
+# Keep Windows timezone data even when Dependabot recompiles this shared lock on Linux.
+tzdata>=2026.5
 opentelemetry-api>=1.44.0
 opentelemetry-sdk>=1.44.0
 tomli>=2.0.1; python_version<"3.11"
-boto3>=1.34.0
+boto3>=1.43.108
 azure-storage-blob>=12.19.0
 google-api-python-client>=2.100.0
 google-auth-httplib2>=0.2.0
diff --git a/.github/requirements/integration.txt b/.github/requirements/integration.txt
index 709249b..4eeebe9 100644
--- a/.github/requirements/integration.txt
+++ b/.github/requirements/integration.txt
@@ -1,5 +1,5 @@
 # This file was autogenerated by uv via the following command:
-#    uv pip compile .github/requirements/integration.in --python-version 3.12 --universal --generate-hashes --only-binary=:all: --exclude-newer 2026-10-02 -o .github/requirements/integration.txt
+#    uv pip compile .github/requirements/integration.in --python-version 3.12 --universal --generate-hashes --only-binary :all: --exclude-newer 2026-10-05T00:00:00Z -o .github/requirements/integration.txt
 azure-core==1.41.0 \
     --hash=sha256:522b4011e8180b1a3dcd2024396a4e7fe9ac37fb8597db47163d230b5efe892d \
     --hash=sha256:f46ff5dfcd230f25cf1c19e8a34b8dc08a337b2503e268bb600a16c00db8ad5a
@@ -73,13 +73,13 @@ bcrypt==5.0.0 \
     --hash=sha256:f8429e1c410b4073944f03bd778a9e066e7fad723564a52ff91841d278dfc822 \
     --hash=sha256:fc746432b951e92b58317af8e0ca746efe93e66555f1b40888865ef5bf56446b
     # via paramiko
-boto3==1.43.107 \
-    --hash=sha256:632a4f8298725b94144c8cd383cbdacb34624daa73221e954c3d33ac6e2528d6 \
-    --hash=sha256:c4e0f1a0295cbb7103f2950128cf88463c076d220080a7d0f127cf834969fc3a
+boto3==1.43.108 \
+    --hash=sha256:03341f089158368acf83e921aca98b706095322ca52bc4c039a616940aa5ad41 \
+    --hash=sha256:19e9da95ef0c494e27052049a42137550e66730509bb613e76eaa30ddf9a7170
     # via -r .github/requirements/integration.in
-botocore==1.43.107 \
-    --hash=sha256:23cbe854e815dbaccf097f7fd32b461c9e1d2ed7e0c7dcc5658218704509d840 \
-    --hash=sha256:4a37fa072a00280c746313532d19b00e2dc53f1993222601df104d71d548d5b6
+botocore==1.43.108 \
+    --hash=sha256:ab9d16c6b4350aaa54ed28202dfa2998b2d735fdbf3247eb60af469d8d48a5b8 \
+    --hash=sha256:ee4f75cf3bdbb0da7912e089950e8112f692016539d939312c771499958e6cfd
     # via
     #   boto3
     #   s3transfer
@@ -1099,9 +1099,9 @@ typing-extensions==4.16.0 \
     #   opentelemetry-api
     #   opentelemetry-sdk
     #   opentelemetry-semantic-conventions
-tzdata==2026.4 ; sys_platform == 'win32' \
-    --hash=sha256:c2169a8b0a7a5e9674da5a135ccdfb2b3e671b333ed9fed17b41f73c34476e81 \
-    --hash=sha256:f1b8bd365d8d210c55353f4d7f8d6d8561c0ba50d704b700d195a9424bba0d79
+tzdata==2026.5 \
+    --hash=sha256:8cc73c0a0bfca7dbfa59235d60b2eff82231dee33f53d206db1acd9173cfc0a7 \
+    --hash=sha256:b683bd1b6659ddcd810ff02ad09ba821d4bf1065072805063eb35c49617905ac
     # via -r .github/requirements/integration.in
 uritemplate==4.2.0 \
     --hash=sha256:480c2ed180878955863323eea31b0ede668795de182617fef9c6ca09e6ec9d0e \
diff --git a/architecture.md b/architecture.md
index d500aaa..5bffabc 100644
--- a/architecture.md
+++ b/architecture.md
@@ -41,7 +41,7 @@ piece of the 1.0 roadmap (`docs/FILEAUTOMATION-1.0-ROADMAP.md`, PR #107); what i
 | `MANIFEST.in` | Keeps `tests/` out of both source distributions (`tests/test_sdist_manifest.py`); package discovery in the TOMLs already keeps it out of the wheels |
 | `scripts/dev_release.py` | Release helper for the dev channel (standard library only): picks the next `automation_file_dev` version from PyPI and tells whether the built wheel differs from the newest published one |
 | `.github/requirements/publish.in`, `publish.txt` | The tools of the two publish jobs (`build`, `twine`, and the build backend `setuptools`) and their hash-locked resolution for Python 3.12 on Linux. `publish.in` holds the `uv pip compile` command that regenerates `publish.txt`; Dependabot reads the directory |
-| `.github/requirements/lint.in`, `lint.txt`, `integration.in`, `integration.txt` | Hash-locked wheel dependencies for lint and Python 3.12 integration jobs. The editable package uses the locked build backend without dependency resolution or build isolation. |
+| `.github/requirements/lint.in`, `lint.txt`, `integration.in`, `integration.txt`, `.pip-tools.toml` | Hash-locked wheel dependencies for lint and Python 3.12 integration jobs. Shared integration inputs retain Windows timezone data on every compiler host; pip-tools configuration keeps the hashed setuptools build backend during Dependabot updates. The editable package uses that backend without dependency resolution or build isolation. |
 | `main_ui.py` | Development shortcut for `launch_ui()` |
 | `tests/`, `docs/`, `examples/mcp/` | pytest suite (fixtures, including the shared Qt application lifecycle, in `tests/conftest.py`); Sphinx docs; MCP host configuration example |
 
diff --git a/docs/updates/2026-10.md b/docs/updates/2026-10.md
index a59a9cb..7acb3e0 100644
--- a/docs/updates/2026-10.md
+++ b/docs/updates/2026-10.md
@@ -756,3 +756,8 @@ Index and query commands: [README.md](README.md). New entries go at the end.
 ## U-20261011-02 · 2026-10-11 · Keep circuit breaker clock fixtures lint clean · #done #ci
 
 Name the clock fixture explicitly and request its side effect through usefixtures where no clock value is used. All eight circuit breaker regression tests pass.
+
+
+## U-20261012-01 · 2026-10-12 · Preserve cross-platform integration dependencies during automated updates · #done #ci
+
+Keep tzdata unconditional in shared integration inputs so Linux-based dependency updates retain Windows timezone data. Add pip-tools configuration for Dependabot and local compilation to retain the hash-locked setuptools build backend. Regenerate the universal Python 3.12 lock with the seven-day release cutoff and add Linux, macOS and Windows compiler regressions. Validation: 37 workflow tests passed; the full local suite passed 5390 tests with 230 optional skips; Ruff lint and format checks passed; mypy reported no issues in 275 source files. Remote service jobs must install the editable package without fetching an unlocked backend.
diff --git a/docs/updates/README.md b/docs/updates/README.md
index 302e9af..4c3193c 100644
--- a/docs/updates/README.md
+++ b/docs/updates/README.md
@@ -58,6 +58,7 @@ In the same commit: delete the item from `progress.md`, add a `#done` entry here
 
 | ID | Date | Title | Tags | Batch |
 |---|---|---|---|---|
+| U-20261012-01 | 2026-10-12 | Preserve cross-platform integration dependencies during automated updates | #done #ci | [2026-10](2026-10.md) |
 | U-20261011-02 | 2026-10-11 | Keep circuit breaker clock fixtures lint clean | #done #ci | [2026-10](2026-10.md) |
 | U-20261011-01 | 2026-10-11 | Integrate open pull requests and stabilize circuit breaker tests | #ci #tests #dependencies | [2026-10](2026-10.md) |
 | U-20261008-39 | 2026-10-08 | The legacy CLI flags exit 1 when an action failed | #feature #cli #testpioneer | [2026-10](2026-10.md) |
@@ -136,5 +137,5 @@ In the same commit: delete the item from `progress.md`, add a `#done` entry here
 
 | File | Period | Entries |
 |---|---|---:|
-| [2026-10.md](2026-10.md) | 2026-10 | 52 |
+| [2026-10.md](2026-10.md) | 2026-10 | 53 |
 | [2026-09.md](2026-09.md) | 2026-09 | 21 |
diff --git a/tests/test_workflow_actions.py b/tests/test_workflow_actions.py
index 4213f30..da04b89 100644
--- a/tests/test_workflow_actions.py
+++ b/tests/test_workflow_actions.py
@@ -219,6 +219,25 @@ def test_lint_and_integration_jobs_cannot_resolve_unlocked_dependencies(workflow
                 assert "--only-binary :all:" in command
 
 
+@pytest.mark.parametrize(
+    "environment",
+    [
+        {"platform_system": "Linux", "sys_platform": "linux"},
+        {"platform_system": "Darwin", "sys_platform": "darwin"},
+        {"platform_system": "Windows", "sys_platform": "win32"},
+    ],
+    ids=["linux-compiler", "macos-compiler", "windows-compiler"],
+)
+def test_shared_integration_inputs_keep_timezone_data_on_every_compiler(environment):
+    """A Linux dependency update must retain Windows timezone data in the shared lock."""
+    lines = (_REQUIREMENTS / "integration.in").read_text(encoding="utf-8").splitlines()
+    requirements = [
+        Requirement(line) for line in lines if line.strip() and not line.startswith("#")
+    ]
+    timezone = next(item for item in requirements if canonicalize_name(item.name) == "tzdata")
+    assert timezone.marker is None or timezone.marker.evaluate(environment)
+
+
 def test_integration_lock_covers_the_package_and_its_build_backend():
     text = (_REQUIREMENTS / "integration.txt").read_text(encoding="utf-8")
     pins = {canonicalize_name(name): version for name, version in _PIN.findall(text)}