diff --git a/.github/workflows/dev-build.yml b/.github/workflows/dev-build.yml
new file mode 100644
index 00000000..1ac2b1cc
--- /dev/null
+++ b/.github/workflows/dev-build.yml
@@ -0,0 +1,380 @@
+name: Dev build
+
+# Development builds for contributors. The point is that a newcomer does not install vcpkg,
+# Boost, Inno Setup and the Windows SDK to try a change; the runner builds, packages and signs,
+# and the artifact is a full installer with a fresh self-signed certificate plus the public key
+# to trust it.
+#
+# Three ways in. A feature-branch push builds automatically, so the artifact is ready when the
+# push finishes. A pull_request run gives reviewers and fork contributors an installer for real
+# device testing -- it uses pull_request, not pull_request_target, deliberately: building the
+# PR's code runs scripts from that code, and pull_request_target would hand those scripts a
+# writable token. workflow_dispatch stays for picking a single component or rebuilding without
+# a push. develop and main never trigger this; they have ci.yml and release.yml.
+#
+# This is a test channel, not a release: the version always carries -dev.<date>.<hash>, the
+# certificate is minted per run, and nothing here creates a release or touches the update
+# manifest. ci.yml remains the merge gate; this workflow deliberately skips the suite the CI
+# already runs and only builds what an installable artifact needs.
+on:
+  workflow_dispatch:
+    inputs:
+      component:
+        description: Which component to build (all = full signed installer)
+        required: true
+        type: choice
+        default: all
+        options:
+          - all
+          - tip
+          - server
+  push:
+    branches-ignore:
+      - develop
+      - main
+      - 'release-please--*'
+      # The Windows 7 port lives in its own repository with dev-build-win7.yml; branches named for
+      # it are pushed here from that work and would only rebuild an artifact nobody asked for.
+      - 'win7*'
+    tags-ignore:
+      - '**'
+    paths-ignore:
+      - '**.md'
+      - 'docs/**'
+  pull_request:
+    branches:
+      - develop
+    paths-ignore:
+      - '**.md'
+      - 'docs/**'
+
+permissions:
+  contents: read
+
+# push and pull_request have no inputs; both build everything, since those events exist to
+# produce an installable artifact and a component filter nobody can set would only mislead.
+
+# Artifacts carry a working installer plus its signing certificate. The default 90-day retention
+# would pile up hundreds of megabytes per push on an active branch, so every upload below passes
+# retention-days: 7 -- enough to notice a build and install it, and the next push replaces it.
+env:
+  DEV_ARTIFACT_RETENTION: 7
+
+# Same ref, newer run wins; an older run keeps burning a runner for nothing.
+concurrency:
+  group: dev-build-${{ github.event_name }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  tip:
+    name: TSF ${{ matrix.name }}
+    if: ${{ (inputs.component || 'all') == 'all' || (inputs.component || 'all') == 'tip' }}
+    runs-on: windows-2025
+    timeout-minutes: 60
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - name: x64
+            architecture: x64
+            triplet: x64-windows-static
+            build_dir: windows/build64-release
+          - name: Win32
+            architecture: Win32
+            triplet: x86-windows-static
+            build_dir: windows/build32-release
+    steps:
+      - name: Check out source
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          submodules: recursive
+      - name: Stamp the dev version into the resource
+        shell: pwsh
+        run: |
+          # YYMMDD in the fourth VERSIONINFO slot: the quad must stay four 16-bit fields, and a
+          # date-compressed value sorts a dev DLL above its own base and below the next release.
+          $base = python scripts/dev-build-version.py --base
+          if ($LASTEXITCODE -ne 0) { exit $LASTEXITCODE }
+          $date = python scripts/dev-build-version.py --date
+          if ($LASTEXITCODE -ne 0) { exit $LASTEXITCODE }
+          python scripts/apply_version.py --version "$base.$date"
+          if ($LASTEXITCODE -ne 0) { exit $LASTEXITCODE }
+      - name: Restore dependency binaries
+        id: vcpkg-cache
+        uses: ./.github/actions/vcpkg-cache
+        with:
+          scope: tip-${{ matrix.triplet }}
+      - name: Install dependencies
+        shell: pwsh
+        working-directory: windows
+        run: vcpkg install --triplet ${{ matrix.triplet }}
+      - name: Save dependency binaries before compiling
+        if: steps.vcpkg-cache.outputs.matched-key != format('{0}-complete', steps.vcpkg-cache.outputs.key)
+        uses: actions/cache/save@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+        with:
+          path: ${{ steps.vcpkg-cache.outputs.path }}
+          key: ${{ steps.vcpkg-cache.outputs.key }}-complete
+      - name: Configure
+        shell: pwsh
+        run: >
+          cmake -S windows -B ${{ matrix.build_dir }} -A ${{ matrix.architecture }}
+          -DCMAKE_TOOLCHAIN_FILE="$env:VCPKG_INSTALLATION_ROOT/scripts/buildsystems/vcpkg.cmake"
+          -DVCPKG_TARGET_TRIPLET=${{ matrix.triplet }}
+      - name: Build
+        shell: pwsh
+        run: cmake --build ${{ matrix.build_dir }} --config Release --parallel
+      - name: Check the Release binary and symbols
+        shell: pwsh
+        run: ./scripts/ci/check-tsf-dll.ps1 -BuildDir '${{ matrix.build_dir }}'
+      - name: Upload the TSF binary and symbols
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: dev-tsf-${{ matrix.name }}
+          retention-days: ${{ env.DEV_ARTIFACT_RETENTION }}
+          # Same layout convention as the release workflow: download-artifact restores the
+          # directory contents where Prepare-PackageFiles.ps1 expects them.
+          path: ${{ matrix.build_dir }}/Release
+          if-no-files-found: error
+
+  server:
+    name: Server
+    if: ${{ (inputs.component || 'all') == 'all' || (inputs.component || 'all') == 'server' }}
+    runs-on: windows-2025
+    timeout-minutes: 90
+    env:
+      SCCACHE_GHA_ENABLED: "true"
+      SCCACHE_IGNORE_SERVER_IO_ERROR: "1"
+    steps:
+      - name: Check out source
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          submodules: recursive
+      - name: Stamp the dev version into the resource
+        # The TSF DLL carries the product's VERSIONINFO even in a server-only build, because the
+        # resource is stamped before configure; keep every build of this run on one version.
+        shell: pwsh
+        run: |
+          $base = python scripts/dev-build-version.py --base
+          if ($LASTEXITCODE -ne 0) { exit $LASTEXITCODE }
+          $date = python scripts/dev-build-version.py --date
+          if ($LASTEXITCODE -ne 0) { exit $LASTEXITCODE }
+          python scripts/apply_version.py --version "$base.$date"
+          if ($LASTEXITCODE -ne 0) { exit $LASTEXITCODE }
+      - name: Restore dependency binaries
+        id: vcpkg-cache
+        uses: ./.github/actions/vcpkg-cache
+        with:
+          scope: server-x64-windows-and-static-md
+      - name: Set up MSVC environment
+        uses: ilammy/msvc-dev-cmd@0b201ec74fa43914dc39ae48a89fd1d8cb592756 # v1.13.0
+      - name: Set up sccache
+        id: sccache
+        continue-on-error: true
+        uses: mozilla-actions/sccache-action@fc920bf0ec8de6ee65d409111f7ec508035751ba # v0.0.11
+      - name: Install Boost
+        shell: pwsh
+        run: ./scripts/ci/install-boost.ps1
+      - name: Save Boost binaries before configuring
+        if: steps.vcpkg-cache.outputs.matched-key != format('{0}-complete', steps.vcpkg-cache.outputs.key) && steps.vcpkg-cache.outputs.matched-key != format('{0}-boost', steps.vcpkg-cache.outputs.key)
+        uses: actions/cache/save@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+        with:
+          path: ${{ steps.vcpkg-cache.outputs.path }}
+          key: ${{ steps.vcpkg-cache.outputs.key }}-boost
+      # Ninja Multi-Config so sccache plugs in through CMAKE_<LANG>_COMPILER_LAUNCHER, mirroring
+      # ci.yml's Server job; the bin/Release layout is what every later step reads. The override
+      # embeds the full dev version string into the native settings page; server/CMakeLists.txt
+      # accepts a semver prerelease suffix, and the about page's ParseVersion strips it for the
+      # update check while displaying it verbatim.
+      - name: Configure
+        shell: pwsh
+        run: |
+          $display = python scripts/dev-build-version.py --display
+          if ($LASTEXITCODE -ne 0) { exit $LASTEXITCODE }
+          $cmakeArgs = @(
+            '-S', 'server', '-B', 'server/build-release', '-G', 'Ninja Multi-Config',
+            "-DCMAKE_TOOLCHAIN_FILE=$env:VCPKG_INSTALLATION_ROOT/scripts/buildsystems/vcpkg.cmake",
+            '-DVCPKG_TARGET_TRIPLET=x64-windows',
+            "-DMSIME_PRODUCT_VERSION_OVERRIDE=$display"
+          )
+          $cmakeArgs += @(./scripts/ci/cmake-sccache-args.ps1 -SetupOutcome '${{ steps.sccache.outcome }}')
+          cmake @cmakeArgs
+          if ($LASTEXITCODE -ne 0) { exit $LASTEXITCODE }
+      - name: Save dependency binaries before compiling
+        if: steps.vcpkg-cache.outputs.matched-key != format('{0}-complete', steps.vcpkg-cache.outputs.key)
+        uses: actions/cache/save@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+        with:
+          path: ${{ steps.vcpkg-cache.outputs.path }}
+          key: ${{ steps.vcpkg-cache.outputs.key }}-complete
+      - name: Build
+        shell: pwsh
+        run: cmake --build server/build-release --config Release --parallel
+      - name: Check the Release binaries and symbols
+        shell: pwsh
+        run: ./scripts/ci/check-server-binaries.ps1 -BuildDir server/build-release/bin/Release
+      - name: Test with the product's exact data
+        shell: pwsh
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: ./scripts/ci/test-server.ps1 -ServerRoot server -StagingRoot "$env:RUNNER_TEMP/product-data" -BuildDir build-release
+      # uiAccess=true is ignored without a signature, so the manifest goes in before upload and
+      # the whole payload gets signed in the package job.
+      - name: Embed the Server uiAccess manifest
+        shell: pwsh
+        run: ./scripts/ci/embed-server-manifest.ps1 -BuildDir server/build-release/bin/Release
+      # component=server uploads this directory as an installable artifact with no package job to
+      # sign it. Windows ignores uiAccess=true without a trusted signature, so the binary would
+      # install and then silently lose the privilege. component=all leaves it unsigned on purpose:
+      # Prepare-PackageFiles.ps1 copies these files into the payload and sign-dev-build.ps1 signs
+      # the copies, so signing here would only add a second signing pass over the same bytes.
+      - name: Sign the Server build for the standalone artifact
+        if: ${{ (inputs.component || 'all') == 'server' }}
+        shell: pwsh
+        env:
+          DEV_CERT_PATH: ${{ runner.temp }}/dev-server-certificate.cer
+        run: |
+          # -Include 只有在 -Path 带通配符或同时给 -Recurse 时才生效，这里显式计算再交给参数，
+          # 免得把一条空列表传进脚本后它才在内部报错。
+          $targets = @(
+            Get-ChildItem -LiteralPath 'server/build-release/bin/Release' -Recurse -File |
+              Where-Object { $_.Extension -in @('.exe', '.dll') } |
+              ForEach-Object FullName
+          )
+          if ($targets.Count -eq 0) { throw 'No EXE or DLL found to sign under server/build-release/bin/Release.' }
+          ./installer/sign-dev-build.ps1 -FilePath $targets
+      - name: Upload the Server build
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: dev-server
+          retention-days: ${{ env.DEV_ARTIFACT_RETENTION }}
+          path: server/build-release/bin/Release
+          if-no-files-found: error
+      # The certificate has to travel with the standalone Server artifact too, or nobody can import
+      # the trust that the signature above depends on.
+      - name: Upload the signing certificate
+        if: ${{ (inputs.component || 'all') == 'server' }}
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: dev-server-certificate
+          retention-days: ${{ env.DEV_ARTIFACT_RETENTION }}
+          path: ${{ runner.temp }}/dev-server-certificate.cer
+          if-no-files-found: error
+
+  package:
+    name: Package installer
+    needs: [tip, server]
+    # Only component=all produces an installer: packaging needs both TSF architectures and the
+    # Server, so there is no meaningful way to package a single-component run.
+    if: ${{ !cancelled() && needs.tip.result == 'success' && needs.server.result == 'success' && (inputs.component || 'all') == 'all' }}
+    runs-on: windows-2025
+    timeout-minutes: 60
+    steps:
+      - name: Check out source
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          submodules: recursive
+      - name: Read the dev version
+        id: version
+        shell: pwsh
+        run: |
+          $display = python scripts/dev-build-version.py --display
+          if ($LASTEXITCODE -ne 0) { exit $LASTEXITCODE }
+          "display=$display" >> $env:GITHUB_OUTPUT
+          "installer=installer/Output/MetasequoiaIME_Setup_v$display.exe" >> $env:GITHUB_OUTPUT
+      - name: Download the x64 TSF binary and symbols
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
+        with:
+          name: dev-tsf-x64
+          path: windows/build64-release/Release
+      - name: Download the 32-bit TSF binary and symbols
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
+        with:
+          name: dev-tsf-Win32
+          path: windows/build32-release/Release
+      - name: Download the Server build
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
+        with:
+          name: dev-server
+          path: server/build-release/bin/Release
+      - name: Download the dictionaries
+        shell: bash
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          STAGING_ROOT: .
+        run: bash scripts/ci/download-dictionaries.sh
+      - name: Build the word-lattice language model
+        shell: pwsh
+        run: ./scripts/build-language-model.ps1
+      - name: Download the neural sentence models
+        shell: pwsh
+        run: ./scripts/fetch-neural-model.ps1
+      - name: Collect the installer payload
+        shell: pwsh
+        working-directory: installer
+        env:
+          TARGET_VERSION: ${{ steps.version.outputs.display }}
+        run: >
+          pwsh -File ./Prepare-PackageFiles.ps1 -TargetVersion $env:TARGET_VERSION
+          -RepoRoot (Resolve-Path '..').Path
+          -TsfDirectory windows -ServerDirectory server -NoticesDirectory .
+          -HelpCodeDirectory engine/helpcode
+      - name: Sign the payload binaries
+        shell: pwsh
+        working-directory: installer
+        env:
+          DEV_CERT_PATH: ${{ runner.temp }}/dev-build.cer
+        run: ./sign-dev-build.ps1
+      - name: Install the Chinese language file for Inno Setup
+        shell: pwsh
+        run: ./scripts/ci/install-inno-language.ps1
+      - name: Compile the installer
+        shell: pwsh
+        working-directory: installer
+        run: pwsh -File ./Compile-Installer.ps1
+      - name: Sign the installer
+        shell: pwsh
+        working-directory: installer
+        env:
+          DEV_CERT_PATH: ${{ runner.temp }}/dev-build.cer
+        run: ./sign-dev-build.ps1 -Installer
+      - name: Name the artifact and record its checksum
+        id: asset
+        shell: pwsh
+        working-directory: installer
+        env:
+          TARGET_VERSION: ${{ steps.version.outputs.display }}
+        run: |
+          $built = "Output/MetasequoiaIME_Setup_v$env:TARGET_VERSION.exe"
+          if (-not (Test-Path $built)) { throw "Inno Setup did not produce $built" }
+          $hash = (Get-FileHash $built -Algorithm SHA256).Hash.ToLower()
+          $size = [math]::Round((Get-Item $built).Length / 1MB, 1)
+          Write-Host "$built ($size MB, sha256 $hash)"
+          "installer_path=$((Resolve-Path $built).Path)" >> $env:GITHUB_OUTPUT
+          "installer_sha256=$hash" >> $env:GITHUB_OUTPUT
+      - name: Upload the installer and the signing certificate
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: dev-installer
+          retention-days: ${{ env.DEV_ARTIFACT_RETENTION }}
+          path: |
+            ${{ steps.asset.outputs.installer_path }}
+            ${{ runner.temp }}/dev-build.cer
+            installer/import-dev-trust.ps1
+          if-no-files-found: error
+      - name: Summarise the build
+        shell: pwsh
+        env:
+          TARGET_VERSION: ${{ steps.version.outputs.display }}
+          INSTALLER_SHA256: ${{ steps.asset.outputs.installer_sha256 }}
+        run: |
+          @(
+            '### Dev build'
+            ''
+            "| Field | Value |"
+            "| --- | --- |"
+            "| Version | $env:TARGET_VERSION |"
+            "| Installer SHA256 | ``$env:INSTALLER_SHA256`` |"
+            ''
+            'To install: download the artifact, unzip, then in an **admin** PowerShell run'
+            '`import-dev-trust.ps1` and launch the installer. Re-run the trust import for every'
+            'new build; the certificate is minted per run and the script replaces the old one.'
+          ) >> $env:GITHUB_STEP_SUMMARY
diff --git a/AGENTS.md b/AGENTS.md
index dd1e0c16..82c92156 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -39,6 +39,8 @@ Server 当前仍使用引擎的兼容 `InputSession`，尚未迁移公共 `Sessi
 
 ## 构建
 
+**用户想编译验证但没装工具链时，优先用 dev-build workflow 而不是让用户装 vcpkg**：特性分支 push 自动触发，PR 会自动跑一次，或 `gh workflow run dev-build.yml --ref <分支> -f component=all` 手动触发，然后 `gh run watch` 等它，`gh run download <runId> -n dev-installer` 拿安装包与证书，安装步骤见 [CONTRIBUTING.md](CONTRIBUTING.md#没有本地工具链时dev-build-workflow)。develop 和 main 不触发；版本号带 `-dev.<日期>.<commit>`，与正式发布隔离。
+
 每个组件是独立的 CMake 工程，各自带 `vcpkg.json` 和 preset，从仓库根目录指定 `-S`：
 
 ```powershell
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index d81b8387..31f838db 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -15,6 +15,27 @@
 
 Boost 按 `-DBoost_ROOT=...` → 环境变量 `BOOST_ROOT` → `%USERPROFILE%\scoop\apps\boost\current` 的顺序解析。preset 里的 vcpkg 路径取自 `$env{VCPKG_ROOT}`，不需要改文件。
 
+### 没有本地工具链时：dev-build workflow
+
+只想验证一个小改动、不想为它装一整套工具链的话，让 CI 编。`Dev build` workflow 平时不跑主分支（develop 和 main 有自己的 CI 和发布流），三种触发方式：
+
+```powershell
+# 特性分支一推就自动编，不需要任何手动操作
+git push -u origin fix/xxx
+
+# 或者手动触发，可选单个组件快速迭代
+gh workflow run dev-build.yml --ref <你的分支> -f component=all
+
+# 等 run 结束拿产物；agent 也可以在这里等
+gh run list --workflow=dev-build.yml --branch <你的分支> --limit 1 --json databaseId,status
+gh run watch <runId> --exit-status
+gh run download <runId> -n dev-installer
+```
+
+开向 develop 的 PR 也会自动跑一次，评审者和 fork 贡献者都能从 PR 的检查页拿到安装包。安装只有两步：管理员 PowerShell 里运行解压出来的 `import-dev-trust.ps1`（导入本次构建的签名证书并清掉上一张），然后双击安装包。版本号带 `-dev.<日期>.<commit>`，一眼可辨，设置页的更新检查不会提示它升级。每次新构建的证书都不同，重装前重跑一次导入脚本即可；产物保留 7 天。
+
+几个边界：`workflow_dispatch` 需要仓库写权限；fork PR 的构建用 `pull_request` 触发（只读 token，无 secrets），首个 run 要维护者点一次批准；`component=tip` 或 `server` 只编译单个组件出裸二进制；这个 workflow 不出 release、不碰更新清单，合并门槛仍然由 PR 上的 CI 把守。
+
 ## 取代码
 
 ```powershell
diff --git a/installer/Prepare-PackageFiles.ps1 b/installer/Prepare-PackageFiles.ps1
index 89e864ab..47546f25 100644
--- a/installer/Prepare-PackageFiles.ps1
+++ b/installer/Prepare-PackageFiles.ps1
@@ -347,6 +347,17 @@ $updatedIss = [regex]::Replace(
     '(?m)^#define\s+MyAppVersion\s+"[^"]+"\s*$',
     "#define MyAppVersion   `"$TargetVersion`""
 )
+# VersionInfoVersion 只接受数字和点号；从目标版本剥掉 -后缀（dev 构建的
+# 0.7.1-dev.20261019.<hash> → 0.7.1），正式版本剥了也原样。
+$versionInfo = ($TargetVersion -replace '-.*$', '')
+if ($versionInfo -notmatch '^[0-9]+(\.[0-9]+)*$') {
+    throw "目标版本剥掉后缀后不是数字版本号，无法写进 VersionInfoVersion：$TargetVersion"
+}
+$updatedIss = [regex]::Replace(
+    $updatedIss,
+    '(?m)^#define\s+MyVersionInfo\s+"[^"]+"\s*$',
+    "#define MyVersionInfo   `"$versionInfo`""
+)
 # .gitattributes pins this repo to eol=lf; emit LF so packaging does not leave the file as a
 # CRLF-only diff that git flags as modified while `git diff` shows no textual change.
 $updatedIss = $updatedIss.TrimEnd("`r", "`n") + "`n"
diff --git a/installer/README.md b/installer/README.md
index 34bd6483..db7be9b5 100644
--- a/installer/README.md
+++ b/installer/README.md
@@ -1,8 +1,9 @@
 # Metasequoia IME Installer
 
-本目录的脚本从 Windows 合仓目录收集产物、签名、用 Inno Setup 打成安装包。它服务两条流程：
+本目录的脚本从 Windows 合仓目录收集产物、签名、用 Inno Setup 打成安装包。它服务三条流程：
 
 - **正式发布**：由 `MSIME-Windows` 的 release workflow 驱动，用真实证书签名包内全部 EXE/DLL 和最终安装包；产物是挂在 Release 上的 `MetasequoiaIME_Setup_v<版本>.exe`，并携带与 Release 二进制匹配的 PDB 符号文件。见下面「CI 契约」
+- **开发构建**：由 `dev-build.yml` workflow 驱动，runner 上现场生成自签名证书并签名，产物随 artifact 分发。见下面「Dev build」
 - **本地测试**：手工跑，用本机自签名证书，用来在自己机器上验证安装流程。本文其余部分讲的是这条
 
 版本号不是固定的，由 `Prepare-PackageFiles.ps1` 的 `-TargetVersion` 决定，默认 `0.0.1`；正式发布时 CI 传入真实版本。
@@ -11,6 +12,16 @@
 
 签名脚本会在你自己的机器上生成并复用一张自签名测试证书。
 
+## Dev build
+
+`dev-build.yml` workflow 给没有本地工具链的贡献者出可安装的包。触发见 [CONTRIBUTING.md](../CONTRIBUTING.md#没有本地工具链时dev-build-workflow)。签名证书由 `sign-dev-build.ps1` 在 runner 上现场生成，subject 固定为 `CN=Metasequoia IME Dev Build Code Signing`，私钥只在 runner 内存里存在一次构建；公钥 `.cer` 随 artifact 分发，用户用 `import-dev-trust.ps1` 导入本机受信任存储（按 subject 清旧导新，重复构建不会膨胀存储）。
+
+- `sign-dev-build.ps1` 复用同一次运行早先创建的证书，所以包内二进制和安装包总在同一签名下；复用的依据是本次运行写在 `RUNNER_TEMP` 里的指纹标记，不按 subject 猜，机器上残留的旧证书不会被误用。`DEV_CERT_PATH` 指出 `.cer` 的导出位置
+- 证书有效期 90 天：artifact 只留 7 天，但用户可能下载到本地后放很久才装，而安装器校验的是签名时刻证书是否有效；`import-dev-trust.ps1` 会打印这张 `.cer` 自带的到期时间，发现已过期就直接退出，不往受信任存储里写
+- `import-dev-trust.ps1` 也随 artifact 分发，用户解压后在管理员 PowerShell 里直接跑
+- 版本号带 `-dev.<日期>.<commit>`，由 `scripts/dev-build-version.py` 从 `version.txt` 派生；设置页的更新检查会剥掉 `-dev` 后缀做数字比较，dev 包不会提示升级
+- 不要把这两个脚本接进 release 路径：正式发布的签名在 `scripts/ci/sign-binaries.ps1` 或 SignPath，两套互不相干
+
 ## CI 契约
 
 根 `.github/workflows/release.yml` **不加修改地调用本目录的 `Prepare-PackageFiles.ps1` 和 `Compile-Installer.ps1`**。源目录名是 `Prepare-PackageFiles.ps1` 的参数，不是写死在脚本里的字面量：默认值为 `windows/`、`server/` 和仓根授权文件；旧目录或自定义布局通过参数覆盖。回归检查同时执行默认路径和显式参数的打包。辅助码默认读取 `engine/helpcode/`，词库缓存位于 `MetasequoiaImeDict/out/`。
@@ -71,7 +82,7 @@ Windows CI 运行 `installer/tests/cloud-choice.ps1`，用 Inno Setup 跑八个
 安装包不携带 VC 运行库，它是系统级共享组件。缺了它 Server 起不来，而这个故障出现在安装结束之后，用户看不到任何解释。所以 `msime_setup.iss` 的 `InitializeSetup` 在安装开始前先查一遍，缺了就当场说清楚，并给出下载地址。界面全部由 `msimeui` 以 Direct2D 绘制，不再依赖 WebView2 Runtime；旧版本留下的 WebView2 用户数据（`ProgramData\metasequoiaime\webview2`、`webview2-settings`，以及 `%LOCALAPPDATA%\metasequoiaime` 下的同名回退目录）由安装器在升级和卸载时清掉。
 
 - **Visual C++ 2015–2022 可再发行组件包（x64）**：读 `Software\Microsoft\VisualStudio\14.0\VC\Runtimes\x64` 的 `Installed` / `Major` / `Minor`，`HKLM32` 和 `HKLM64` 两个视图都查。要求 **14.40 以上**（常量 `VCRuntimeMinMinor`）：`server_exe\` 里的 exe 用 MSVC 14.40+（VS 2022 17.10 起）编译并导入 `msvcp140.dll`，这一版起 `std::mutex` 的构造函数是 constexpr，配上更旧的 `msvcp140.dll` 会在第一次加锁时访问冲突、无声闪退——设置页「点了没反应」就是这个现象。装了 2019 / 早期 2022 运行库的机器同样有 `Installed=1`，所以必须比版本号。构建工具链升级到要求更高 redist 时同步调高这个常量。32 位 TSF DLL 用静态 CRT（`windows/CMakeLists.txt` 的 `CMAKE_MSVC_RUNTIME_LIBRARY`），所以不检查 x86 redist
-- **不要改成查 `System32` 里的 DLL。** Setup.exe 是 32 位进程，Pascal Script 的 `FileExists` 会被 WOW64 重定向到 `SysWOW64`，查到的是 x86 运行库；只装了 x64 redist 的机器会被误判成缺少 x64 运行库。绕开重定向的办法不可移植：`EnableFsRedirection` 在 Inno Setup 7 里已被移除，而它的替代品在 CI 用的 6.x 里还不存在
+- **不要改成查 `System32` 里的 DLL，也不要在 Pascal Script 里用 `ApplyPathRedirRulesForCurrentProcess`。** 那是 Inno Setup 7 的 support function，CI 的 6.7.1 没有它，ISCC 会报 `Unknown identifier`（#925 引入后第一次在 hosted runner 上编安装包就炸了，#55e1127a 改回直接展开 `{sys}`）。Setup 在 x64/ARM64 上是 64 位进程，`{sys}` 本来就不经重定向；需要 32 位视图时用 `{syswow64}`
 - 缺组件或版本过旧时弹一次对话框，区分「没装」和「已装 x.y 但过旧」，列出直接下载链接（`https://aka.ms/vc14/vc_redist.x64.exe`）和说明页：选「是」直接下载安装包并结束安装，选「否」继续装。**不阻断安装**——用户可能马上就要去补组件，也可能只是在准备环境。静默安装（CI、批量部署）用 `SuppressibleMsgBox` 默认「否」直接继续，缺什么已经写进安装日志（`/LOG=`）
 
 ## 依赖
diff --git a/installer/import-dev-trust.ps1 b/installer/import-dev-trust.ps1
new file mode 100644
index 00000000..5bd70144
--- /dev/null
+++ b/installer/import-dev-trust.ps1
@@ -0,0 +1,94 @@
+# 信任一张 dev-build 签名证书并清理旧证书。
+#
+# CI 的 dev-build workflow 每次运行现场生成一张自签名代码签名证书，签完整包后把公钥
+# （.cer）放进 artifact。指纹每次都变，但 subject 固定，所以本脚本先把本地受信任存储里
+# 旧 subject 的证书清掉，再导入新证书，测试机的受信任根不会随构建次数膨胀。
+#
+# 用管理员 PowerShell 运行（写 LocalMachine 存储需要提升）：
+#   pwsh -File .\import-dev-trust.ps1 [-CertificatePath .\dev-build.cer] [-Keep]
+#
+# 导入完成就可以安装同目录下的 MetasequoiaIME_Setup_v*-dev.*.exe。
+# -Keep 保留旧证书不清理（排查签名问题时用）。
+[CmdletBinding()]
+param(
+    # 默认取脚本同目录下唯一的 .cer；有多个时报错让用户指定，避免导错文件。
+    [string]$CertificatePath,
+    [switch]$Keep
+)
+
+$ErrorActionPreference = 'Stop'
+Set-StrictMode -Version Latest
+
+$Subject = 'CN=Metasequoia IME Dev Build Code Signing'
+$TrustStores = @('Cert:\LocalMachine\Root', 'Cert:\LocalMachine\TrustedPublisher')
+
+function Test-Administrator {
+    $identity = [System.Security.Principal.WindowsIdentity]::GetCurrent()
+    $principal = [System.Security.Principal.WindowsPrincipal]::new($identity)
+    return $principal.IsInRole([System.Security.Principal.WindowsBuiltInRole]::Administrator)
+}
+
+if (-not $CertificatePath) {
+    $candidates = @(
+        Get-ChildItem -LiteralPath $PSScriptRoot -Filter '*.cer' -File -ErrorAction SilentlyContinue
+    )
+    if ($candidates.Count -eq 0) {
+        throw "当前目录没有 .cer 文件。请把 dev-build artifact 解压后在本目录运行：$PSScriptRoot"
+    }
+    if ($candidates.Count -gt 1) {
+        throw "发现多个 .cer 文件，请用 -CertificatePath 指定一个：$($candidates.Name -join ', ')"
+    }
+    $CertificatePath = $candidates[0].FullName
+}
+if (-not (Test-Path -LiteralPath $CertificatePath -PathType Leaf)) {
+    throw "证书文件不存在：$CertificatePath"
+}
+
+$certificate = New-Object System.Security.Cryptography.X509Certificates.X509Certificate2($CertificatePath)
+if ($certificate.Subject -ne $Subject) {
+    throw "这不是 dev-build 签名证书（subject：$($certificate.Subject)）。预期：$Subject"
+}
+
+# 到期时间读的是这张 .cer 自带的字段，不靠「构建过了几天」去推。签名在证书有效期内完成才能
+# 通过校验，所以证书过期后这份包就装不上了，导入得再干净也没用，必须换新构建。
+# 这一步必须排在写受信任存储之前：过期证书导入进去只会让本机多一条无用的信任记录。
+if ($certificate.NotAfter -le (Get-Date)) {
+    Write-Warning "这张证书已经过期（$($certificate.NotAfter.ToString('yyyy-MM-dd HH:mm'))），包内签名无法通过校验。"
+    Write-Warning '请重新下载最新的 dev build，用它的证书和安装包；不要继续安装当前这份。'
+    exit 1
+}
+
+# 权限检查放在体检之后：先让没提升权限的用户知道包本身已经过期，再告诉他去开管理员。
+if (-not (Test-Administrator)) {
+    throw '需要管理员 PowerShell：写入 LocalMachine 受信任存储必须提升权限。'
+}
+
+# 按固定 subject 清理所有旧证书，再导入新的一张。跳过与本次导入指纹相同的那份。
+if (-not $Keep) {
+    foreach ($store in $TrustStores) {
+        $stale = @(Get-ChildItem -Path $store -ErrorAction SilentlyContinue |
+            Where-Object { $_.Subject -eq $Subject -and $_.Thumbprint -ne $certificate.Thumbprint })
+        foreach ($old in $stale) {
+            Remove-Item -LiteralPath ("{0}\{1}" -f $store, $old.Thumbprint) -Force
+            Write-Host "已移除旧 dev 证书：$($old.Thumbprint)（$store）"
+        }
+    }
+}
+
+$temporaryFile = Join-Path ([IO.Path]::GetTempPath()) ('msime-dev-trust-' + [Guid]::NewGuid() + '.cer')
+try {
+    [IO.File]::Copy($CertificatePath, $temporaryFile, $true)
+    foreach ($store in $TrustStores) {
+        Import-Certificate -FilePath $temporaryFile -CertStoreLocation $store | Out-Null
+        Write-Host "已信任：$store"
+    }
+}
+finally {
+    Remove-Item -LiteralPath $temporaryFile -Force -ErrorAction SilentlyContinue
+}
+
+Write-Host ''
+Write-Host "Dev 证书已就绪：$($certificate.Subject)"
+Write-Host "指纹：$($certificate.Thumbprint)（本次构建专有，换新 build 需重跑本脚本）"
+Write-Host "有效期至：$($certificate.NotAfter.ToString('yyyy-MM-dd HH:mm'))（本机时间）"
+Write-Host '现在可以安装同目录下的 dev 安装包了。'
diff --git a/installer/msime_setup.iss b/installer/msime_setup.iss
index 7030fdbb..9fbbac84 100644
--- a/installer/msime_setup.iss
+++ b/installer/msime_setup.iss
@@ -20,6 +20,10 @@
 
 #define MyAppName      "Metasequoia IME 水杉输入法"
 #define MyAppVersion   "0.0.1"
+; VersionInfoVersion 是 PE 的 VERSIONINFO，只接受数字和点号；dev 构建的 MyAppVersion 带
+; -dev.<日期>.<hash> 后缀（Prepare-PackageFiles.ps1 会把数字部分同步写进这个 define），
+; 文件名与 AppVersion 用完整串，这里只用数字段。
+#define MyVersionInfo  "0.0.1"
 #define MyAppPublisher "Metasequoia"
 #define MyAppExeName   "MetasequoiaImeServer.exe"
 #define MySettingsExeName "MetasequoiaImeSettings.exe"
@@ -36,7 +40,11 @@
 #define MySourceRoot   "."
 ; TSF DLL 装在系统目录下：CS2 等开启 Trusted Mode 的游戏只放行「位于系统目录且有代码签名」的
 ; 第三方 in-proc DLL，装在 Program Files 的 DLL 连加载都会被拒，输入法在游戏里根本切不出来。
-; 本安装器是 32 位进程，[Code] 里访问 64 位那份要先过 ApplyPathRedirRulesForCurrentProcess。
+; 本安装器在 x64/ARM64 上以 64 位模式运行（ArchitecturesInstallIn64BitMode），
+; Pascal Script 里访问 {sys} 就是真正的 System32，没有 WOW64 重定向可绕。
+; 不要在这里用 ApplyPathRedirRulesForCurrentProcess：那是 Inno Setup 7 的 support
+; function，windows-2025 runner 的 6.7.1 没有它，ISCC 直接报 Unknown identifier
+; （#925 引入后第一次在 hosted runner 上编安装包就炸了，见 installer/README.md）。
 #define MyTsfRoot64    "{sys}\IME\MetasequoiaIME"
 #define MyTsfRoot32    "{syswow64}\IME\MetasequoiaIME"
 #ifdef LightPackage
@@ -69,7 +77,7 @@ ArchitecturesAllowed=x64compatible
 ArchitecturesInstallIn64BitMode=x64compatible
 UninstallDisplayName={#MyAppName}
 UninstallDisplayIcon={commonpf64}\metasequoiaime\MetasequoiaIME.ico
-VersionInfoVersion={#MyAppVersion}
+VersionInfoVersion={#MyVersionInfo}
 
 [Languages]
 Name: "chinesesimplified"; MessagesFile: "compiler:Languages\ChineseSimplified.isl"
@@ -718,10 +726,10 @@ begin
       '现有数据将从这里迁移：' + NewLine + Space + ResolvePreviousDataDir;
 end;
 
-{ 本进程能直接访问的 TSF 根目录。32 位安装器里不经改写的 System32 会被 WOW64 落到 SysWOW64。}
+// 本进程能直接访问的 TSF 根目录。64 位模式下 sys 常量不经重定向，直接就是 System32。
 function TsfRoot64: String;
 begin
-  Result := ApplyPathRedirRulesForCurrentProcess(True, ExpandConstant('{#MyTsfRoot64}'));
+  Result := ExpandConstant('{#MyTsfRoot64}');
 end;
 
 function TsfRoot32: String;
diff --git a/installer/sign-dev-build.ps1 b/installer/sign-dev-build.ps1
new file mode 100644
index 00000000..ef84507c
--- /dev/null
+++ b/installer/sign-dev-build.ps1
@@ -0,0 +1,170 @@
+# 在 runner 上现场生成自签名代码签名证书，签 dev-build 的包内二进制与安装包。
+#
+# dev-build workflow 每次运行生成一张新证书，私钥只存在于 runner 内存中，运行结束即消失；
+# 公钥导出成 .cer 进 artifact，由用户用 import-dev-trust.ps1 导入本机受信任存储。
+# uiAccess=true 的 Server 没有可信签名会被 Windows 忽略，所以签名是 dev 包可用的前提。
+#
+# 环境变量：DEV_CERT_PATH（.cer 输出路径）。在 installer/ 目录下运行，与
+# Sign-PackageBinaries-Local.ps1 相同的待签集合（server_exe/ 与 tsf_dll/ 下全部 EXE/DLL）。
+#
+#   pwsh -File .\sign-dev-build.ps1                       # 签包内二进制
+#   pwsh -File .\sign-dev-build.ps1 -Installer            # 签编译完成的安装包
+#   pwsh -File .\sign-dev-build.ps1 -FilePath a.exe,b.exe # 签显式列出的文件（server 单独构建用）
+[CmdletBinding()]
+param(
+    [switch]$Installer,
+    [string[]]$FilePath
+)
+
+$ErrorActionPreference = 'Stop'
+Set-StrictMode -Version Latest
+
+$CertificateSubject = 'CN=Metasequoia IME Dev Build Code Signing'
+
+function Find-SignTool {
+    $kitsBin = Join-Path ${env:ProgramFiles(x86)} 'Windows Kits\10\bin'
+    $candidate = Get-ChildItem -LiteralPath $kitsBin -Directory -ErrorAction SilentlyContinue |
+        Sort-Object { try { [version]$_.Name } catch { [version]'0.0' } } -Descending |
+        ForEach-Object { Join-Path $_.FullName 'x64\signtool.exe' } |
+        Where-Object { Test-Path -LiteralPath $_ -PathType Leaf } |
+        Select-Object -First 1
+    if (-not $candidate) {
+        throw 'signtool.exe not found in the Windows SDK.'
+    }
+    return $candidate
+}
+
+# 同一次运行里重复调用本脚本时复用签名步骤生成的证书，保持包内二进制与安装包同一签名。
+#
+# 复用的判断必须来自「本次运行写入的标记」，不能只靠「证书看起来像 dev 证书」：改了 subject
+# 之后，任何一台没被重置的机器上都会留下上次构建的证书，有效期 30 天，subject 和 EKU 全都
+# 对得上。只按属性筛就会把上一个任务生成的私钥拿来签名，产出的包属于别的流水线。标记文件
+# 放在 RUNNER_TEMP 下（托管 runner 每次都是新的临时目录），内容就是本次要复用的指纹。
+function Get-RunMarkerPath {
+    $root = if ($env:RUNNER_TEMP) { $env:RUNNER_TEMP } else { [IO.Path]::GetTempPath() }
+    return Join-Path $root 'msime-dev-build-certificate.thumbprint'
+}
+
+function Get-RunCertificate {
+    $marker = Get-RunMarkerPath
+    if (-not (Test-Path -LiteralPath $marker -PathType Leaf)) {
+        return $null
+    }
+    $thumbprint = (Get-Content -LiteralPath $marker -Raw -ErrorAction SilentlyContinue)
+    if ($thumbprint) { $thumbprint = $thumbprint.Trim() }
+    if (-not $thumbprint) {
+        return $null
+    }
+    $certificate = Get-ChildItem -Path 'Cert:\CurrentUser\My' -ErrorAction SilentlyContinue |
+        Where-Object { $_.Thumbprint -eq $thumbprint -and $_.HasPrivateKey } |
+        Select-Object -First 1
+    if (-not $certificate) {
+        # 标记在但证书没了（比如被清理）：当作本次没有证书，重新生成并覆盖标记。
+        Write-Host "The certificate recorded for this run is gone from the store: $thumbprint"
+    }
+    return $certificate
+}
+
+function New-RunCertificate {
+    # -Type CodeSigningCert 负责代码签名 EKU。有效期权衡的是两件事：artifact 只留 7 天，
+    # 但用户可能下载到本地后放很久才装，而安装器检查的是签名时刻证书是否有效；拉得太长又会
+    # 让一张随构建轮换的证书变成长期可信身份。90 天覆盖到拖延的安装，又不至于成为长期凭据。
+    # import-dev-trust.ps1 会打印实际的到期时间，安装器发现包内证书过期时也会明确报出来。
+    $certificate = New-SelfSignedCertificate `
+        -Type CodeSigningCert `
+        -Subject $CertificateSubject `
+        -FriendlyName 'Metasequoia IME Dev Build Code Signing' `
+        -KeyAlgorithm RSA `
+        -KeyLength 3072 `
+        -HashAlgorithm SHA256 `
+        -KeyUsage DigitalSignature `
+        -CertStoreLocation 'Cert:\CurrentUser\My' `
+        -NotBefore (Get-Date).AddHours(-1) `
+        -NotAfter (Get-Date).AddDays(90)
+    return $certificate
+}
+
+$certificate = Get-RunCertificate
+if ($certificate) {
+    Write-Host "Reusing the certificate created earlier in this run: $($certificate.Thumbprint)"
+}
+else {
+    $certificate = New-RunCertificate
+    # 先落标记再往下走：后面任何一步失败重跑，都应该复用这一张而不是再生成一张。
+    Set-Content -LiteralPath (Get-RunMarkerPath) -Value $certificate.Thumbprint -NoNewline -Encoding utf8NoBOM
+    Write-Host "Created the dev-build signing certificate: $($certificate.Thumbprint)"
+}
+
+$certPath = $env:DEV_CERT_PATH
+if (-not $certPath) {
+    throw 'DEV_CERT_PATH is not set; the workflow must say where to export the public key.'
+}
+$certDirectory = Split-Path -Parent $certPath
+if (-not (Test-Path -LiteralPath $certDirectory -PathType Container)) {
+    New-Item -ItemType Directory -Path $certDirectory -Force | Out-Null
+}
+Export-Certificate -Cert $certificate -FilePath $certPath -Type CERT -Force | Out-Null
+Write-Host "Public key exported to $certPath"
+
+$signTool = Find-SignTool
+
+if ($Installer) {
+    $candidates = @(Get-ChildItem -LiteralPath (Join-Path $PSScriptRoot 'Output') -Filter '*.exe' -File -ErrorAction SilentlyContinue)
+    if ($candidates.Count -eq 0) {
+        throw 'No installer found under Output\. Compile it first.'
+    }
+    if ($candidates.Count -gt 1) {
+        throw "Multiple installers under Output\, refusing to guess: $($candidates.Name -join ', ')"
+    }
+    $targets = @($candidates[0].FullName)
+}
+elseif ($FilePath) {
+    $targets = @(
+        foreach ($item in $FilePath) {
+            if (-not (Test-Path -LiteralPath $item -PathType Leaf)) {
+                throw "File to sign does not exist: $item"
+            }
+            (Resolve-Path -LiteralPath $item).Path
+        }
+    )
+}
+else {
+    $packageDirectories = @(
+        (Join-Path $PSScriptRoot 'server_exe'),
+        (Join-Path $PSScriptRoot 'tsf_dll')
+    )
+    foreach ($directory in $packageDirectories) {
+        if (-not (Test-Path -LiteralPath $directory -PathType Container)) {
+            throw "Missing staging directory, run Prepare-PackageFiles.ps1 first: $directory"
+        }
+    }
+    # 最外层的 @() 不能省：只有一个待签文件时管道结果是标量，.Count 在严格模式下会报错。
+    $targets = @(
+        @(
+            foreach ($directory in $packageDirectories) {
+                Get-ChildItem -LiteralPath $directory -Recurse -File |
+                    Where-Object { $_.Extension -in @('.exe', '.dll') }
+            }
+        ) | Sort-Object FullName -Unique
+    ) | ForEach-Object { $_.FullName }
+    if ($targets.Count -eq 0) {
+        throw 'No EXE or DLL found to sign.'
+    }
+}
+
+$thumbprint = $certificate.Thumbprint
+Write-Host "Signing $($targets.Count) file(s) with $thumbprint"
+# 自签名证书的时间戳没有意义（测试机可能离线，且证书随 build 轮换），所以不加 /tr。
+& $signTool sign /sha1 $thumbprint /s My /fd sha256 /v @($targets)
+if ($LASTEXITCODE -ne 0) {
+    throw "signtool.exe signing failed with exit code $LASTEXITCODE"
+}
+
+foreach ($target in $targets) {
+    $signature = Get-AuthenticodeSignature -LiteralPath $target
+    if (-not $signature.SignerCertificate -or
+        $signature.SignerCertificate.Thumbprint -ne $thumbprint) {
+        throw "Signature missing or signed by the wrong certificate: $target"
+    }
+}
+Write-Host "Signed $($targets.Count) file(s); every signature verified against the dev certificate."
diff --git a/scripts/apply_version.py b/scripts/apply_version.py
index e76925cb..0dd558d4 100644
--- a/scripts/apply_version.py
+++ b/scripts/apply_version.py
@@ -5,7 +5,8 @@ release-please owns version.txt. The VERSIONINFO block in windows/src/IME/Metase
 same number in two shapes, a comma-separated quad and a dotted string, so it cannot be driven by
 release-please's generic updater. The release workflow runs this before configuring CMake.
 
-The fourth field of the quad stays 0; only MAJOR.MINOR.PATCH are release-managed.
+The fourth field of the quad stays 0 for releases; a dev build passes an explicit
+--version MAJOR.MINOR.PATCH.YYMMDD to stamp its date there.
 
     python scripts/apply_version.py                    # stamp from version.txt
     python scripts/apply_version.py --check            # exit 1 if the resource is out of date
@@ -23,7 +24,7 @@ REPO_ROOT = Path(__file__).resolve().parents[1]
 VERSION_FILE = REPO_ROOT / "version.txt"
 RESOURCE_FILE = REPO_ROOT / "windows" / "src" / "IME" / "MetasequoiaIME.rc"
 
-SEMVER = re.compile(r"^(\d+)\.(\d+)\.(\d+)$")
+SEMVER = re.compile(r"^(\d+)\.(\d+)\.(\d+)(?:\.(\d+))?$")
 
 # Each pattern captures the part before the version and the part after it, so only the digits move.
 SUBSTITUTIONS = (
@@ -34,7 +35,7 @@ SUBSTITUTIONS = (
 )
 
 
-def read_version(explicit_version: str | None = None) -> tuple[str, str, str]:
+def read_version(explicit_version: str | None = None) -> tuple[str, str, str, str]:
     if explicit_version is None:
         if not VERSION_FILE.is_file():
             raise SystemExit(f"error: {VERSION_FILE} is missing")
@@ -45,13 +46,17 @@ def read_version(explicit_version: str | None = None) -> tuple[str, str, str]:
         source = "--version"
     match = SEMVER.match(raw)
     if not match:
-        raise SystemExit(f"error: {source} must hold MAJOR.MINOR.PATCH, got {raw!r}")
-    return match.groups()
+        raise SystemExit(
+            f"error: {source} must hold MAJOR.MINOR.PATCH[.BUILD], got {raw!r}"
+        )
+    # The optional fourth field carries a dev build's YYMMDD stamp; releases leave it at 0.
+    major, minor, patch, build_field = match.groups()
+    return major, minor, patch, build_field or "0"
 
 
-def render(version: tuple[str, str, str]) -> tuple[str, str]:
-    major, minor, patch = version
-    return f"{major},{minor},{patch},0", f"{major}.{minor}.{patch}.0"
+def render(version: tuple[str, str, str, str]) -> tuple[str, str]:
+    major, minor, patch, build_field = version
+    return f"{major},{minor},{patch},{build_field}", f"{major}.{minor}.{patch}.{build_field}"
 
 
 def apply(text: str, quad: str, dotted: str) -> tuple[str, int]:
diff --git a/scripts/dev-build-version.py b/scripts/dev-build-version.py
new file mode 100644
index 00000000..df31cf65
--- /dev/null
+++ b/scripts/dev-build-version.py
@@ -0,0 +1,100 @@
+#!/usr/bin/env python3
+"""Derive the dev-build version from version.txt.
+
+The release owns version.txt (release-please), and dev builds must never masquerade as one.
+The dev number keeps the release base for human recognition and appends a date and the short
+commit: 0.7.1-dev.20261019.7fa6fb1a.
+
+The strings go to the installer name and the settings page. The TSF DLL's VERSIONINFO quad has
+four 16-bit fields, so the date compresses to YYMMDD in the fourth slot: 0.7.1.261019. yy > 79
+sorts above every year this product exists, and any real release leaves that slot at 0, so a dev
+DLL always reads as newer than its own base and older than the next release. The settings page's
+parseVersion strips the -dev suffix and compares 0.7.1, which is why the update check stays quiet.
+
+Windows filenames and Inno Setup accept the dots in the short hash; a detached HEAD (workflow
+dispatch on a raw SHA) falls back to the first twelve hex digits.
+
+    python scripts/dev-build-version.py                  # all three outputs, one per line
+    python scripts/dev-build-version.py --display        # 0.7.1-dev.20261019.7fa6fb1a
+    python scripts/dev-build-version.py --base           # 0.7.1
+    python scripts/dev-build-version.py --date           # 261019
+"""
+
+from __future__ import annotations
+
+import argparse
+import datetime
+import re
+import subprocess
+import sys
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+VERSION_FILE = REPO_ROOT / "version.txt"
+
+SEMVER = re.compile(r"^(\d+)\.(\d+)\.(\d+)$")
+SHORT_SHA = re.compile(r"^[0-9a-f]{7,40}$")
+
+
+def read_base() -> tuple[str, str, str]:
+    if not VERSION_FILE.is_file():
+        raise SystemExit(f"error: {VERSION_FILE} is missing")
+    raw = VERSION_FILE.read_text(encoding="utf-8").strip()
+    match = SEMVER.match(raw)
+    if not match:
+        raise SystemExit(f"error: version.txt must hold MAJOR.MINOR.PATCH, got {raw!r}")
+    return match.groups()
+
+
+def read_short_sha(explicit: str | None) -> str:
+    if explicit:
+        sha = explicit.strip().lower()
+        if not SHORT_SHA.match(sha):
+            raise SystemExit(f"error: --commit must be hex digits, got {explicit!r}")
+        return sha[:12]
+    result = subprocess.run(
+        ["git", "rev-parse", "--short=12", "HEAD"],
+        cwd=REPO_ROOT,
+        capture_output=True,
+        text=True,
+    )
+    if result.returncode != 0:
+        raise SystemExit(f"error: cannot read the commit: {result.stderr.strip()}")
+    return result.stdout.strip()
+
+
+def build(base: tuple[str, str, str], today: datetime.date, sha: str) -> tuple[str, str]:
+    major, minor, patch = base
+    display = f"{major}.{minor}.{patch}-dev.{today:%Y%m%d}.{sha}"
+    # 四段 quad 的末位放 YYMMDD：YY > 79 恒大于本产品存在的一切年份，任何正式版该位是 0，
+    # 所以 dev DLL 恒读作比基线新、比下一个发布旧。
+    date = today.strftime("%y%m%d")
+    quad = f"{major}.{minor}.{patch}.{date}"
+    return display, date
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
+    output = parser.add_mutually_exclusive_group()
+    output.add_argument("--display", action="store_true", help="print the display version only")
+    output.add_argument("--base", action="store_true", help="print the base version only")
+    output.add_argument("--date", action="store_true", help="print the YYMMDD stamp only")
+    parser.add_argument("--commit", metavar="SHA", help="use this short commit instead of reading git")
+    args = parser.parse_args()
+
+    base = read_base()
+    display, date = build(base, datetime.date.today(), read_short_sha(args.commit))
+    if args.display:
+        print(display)
+    elif args.base:
+        print(".".join(base))
+    elif args.date:
+        print(date)
+    else:
+        print(display)
+        print(date)
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/server/CMakeLists.txt b/server/CMakeLists.txt
index 56937097..56f90b5f 100644
--- a/server/CMakeLists.txt
+++ b/server/CMakeLists.txt
@@ -43,7 +43,10 @@ else()
     file(STRINGS "${MSIME_VERSION_FILE}" MSIME_PRODUCT_VERSION LIMIT_COUNT 1)
 endif()
 string(STRIP "${MSIME_PRODUCT_VERSION}" MSIME_PRODUCT_VERSION)
-if(NOT MSIME_PRODUCT_VERSION MATCHES "^[0-9]+(\\.[0-9]+)*$")
+# 版本主体必须是数字段；允许一个可选的连字符后缀（semver 预发布段），dev-build 用它携带
+# 日期与 commit（0.7.1-dev.20261019.<hash>），设置窗口关于页原样显示。关于页的 ParseVersion
+# 会剥掉后缀做更新检查的数字比较，所以后缀不影响版本判定。
+if(NOT MSIME_PRODUCT_VERSION MATCHES "^[0-9]+(\\.[0-9]+)*(-[0-9A-Za-z.-]+)?$")
     message(FATAL_ERROR "Invalid product version in ${MSIME_VERSION_FILE}: '${MSIME_PRODUCT_VERSION}'")
 endif()
 configure_file(
diff --git a/server/scripts/lcompile-release.ps1 b/server/scripts/lcompile-release.ps1
index a112b0bb..e77a3473 100644
--- a/server/scripts/lcompile-release.ps1
+++ b/server/scripts/lcompile-release.ps1
@@ -2,7 +2,7 @@
 [CmdletBinding()]
 param(
     [string]$ManifestTool = 'C:\Program Files (x86)\Windows Kits\10\bin\10.0.26100.0\x64\mt.exe',
-    [ValidatePattern('^\d+\.\d+\.\d+$')]
+    [ValidatePattern('^\d+\.\d+\.\d+(-[0-9A-Za-z.-]+)?$')]
     [string]$ProductVersion = '',
     # ALL_BUILD also builds MetasequoiaImeServerTests and test_webview_contract, which the packaging
     # step deletes again. The server target already depends on the watchdog, the three panels,