@@ -0,0 +1,55 @@
+root = true
+
+# Language indent/EOL/charset overlap with .vscode/settings.json.
+# Rulers, renderWhitespace, detectIndentation, mergeEditor, and
+# language-server settings cannot be expressed here — they stay in
+# settings.json.
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 2
+indent_style = tab
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+# [bat]
+[*.{bat,cmd}]
+end_of_line = crlf
+indent_size = 4
+indent_style = space
+
+# [c]
+[*.{c,h}]
+indent_size = 4
+indent_style = space
+
+# [cmake]
+[{CMakeLists.txt,*.cmake}]
+indent_size = 4
+indent_style = tab
+
+# [cpp]
+[*.{cpp,cxx,hpp,hxx}]
+indent_size = 4
+indent_style = space
+
+# [json]
+[*.json]
+indent_size = 2
+indent_style = space
+
+# [markdown]
+[*.md]
+indent_size = 2
+indent_style = space
+
+# [shellscript]
+[*.{bash,sh,zsh}]
+indent_size = 2
+indent_style = space
+
+# [yaml]
+[*.{yaml,yml}]
+indent_size = 2
+indent_style = space
@@ -1,22 +1,126 @@
-*.c linguist-language=C
-*.h linguist-language=C
+# .gitattributes — C / C++ (GitHub-hosted)
+#
+# Sources: GitHub Docs (line endings), git-scm gitattributes (diff=cpp),
+# gitattributes/gitattributes C++.gitattributes + Common.gitattributes,
+# github-linguist overrides.
+#
+# Linguist language-bar policy (Synesis): classify public C API headers as C
+# and *.cmake as CMake scripts; keep helper scripts, IDE project files, and
+# CMakeLists.txt config out of the advertised language mix. Prefer
+# -linguist-detectable over linguist-detectable=false.
 
-*.cpp linguist-language=C++
-*.hpp linguist-language=C++
-*.cxx linguist-language=C++
-*.hxx linguist-language=C++
+# Default: detect text, normalize to LF in the repository
+* text=auto
 
-*.cmake linguist-language=CMake
+# --- Source ---
+*.c text diff=cpp
+*.c++ text diff=cpp
+*.cc text diff=cpp
+*.cpp text diff=cpp
+*.cxx text diff=cpp
+*.h text diff=cpp
+*.h++ text diff=cpp
+*.hh text diff=cpp
+*.hpp text diff=cpp
+*.hxx text diff=cpp
+*.inc text
+*.inl text
+*.ipp text
+*.tcc text
+*.tpp text
+
+# --- Build / config ---
+*.am text
+*.cmake text
+*.m4 text
+*.mak text
+*.mk text
+*akefile text
+CMakeLists.txt text
+configure text eol=lf
+configure.ac text
+
+# --- Scripts ---
+*.bash text eol=lf
+*.bat text eol=crlf
+*.cmd text eol=crlf
+*.ps1 text eol=crlf
+*.sh text eol=lf
+*.zsh text eol=lf
+
+# --- Docs / meta ---
+*.adoc text
+*.markdown text diff=markdown
+*.md text diff=markdown
+*.txt text
+AUTHORS text
+CHANGELOG text
+CHANGES text
+CONTRIBUTING text
+COPYING text
+LICENSE text
+NEWS text
+README text
+TODO text
+.gitattributes text
+.gitignore text
 
-*.cmd linguist-detectable=false
-*.html linguist-detectable=false
-*.sh linguist-detectable=false
-*.dsp linguist-detectable=false
-*.dsw linguist-detectable=false
-*.sln linguist-detectable=false
-*.vimrc linguist-detectable=false
-*.vcxproj linguist-detectable=false
+# --- Serialisation ---
+*.json text
+*.toml text
+*.xml text
+*.yaml text
+*.yml text
 
-CMakeLists.txt linguist-language=CMake
-makefile linguist-detectable=false
+# --- Compiled / binary artefacts ---
+*.a binary
+*.dll binary
+*.dylib binary
+*.exe binary
+*.gch binary
+*.la binary
+*.lai binary
+*.lib binary
+*.lo binary
+*.o binary
+*.obj binary
+*.out binary
+*.pch binary
+*.slo binary
+*.so binary
+
+# --- Archives / images (common) ---
+*.gif binary
+*.gz binary
+*.ico binary
+*.jpeg binary
+*.jpg binary
+*.png binary
+*.tar binary
+*.zip binary
+
+# --- GitHub Linguist ---
+**/build/** linguist-generated
+**/cmake-build-*/** linguist-generated
+
+# Classification (C-primary / C API with C++ tests; *.cmake as CMake scripts)
+*.c linguist-language=C
+*.cmake linguist-language=CMake
+*.cpp linguist-language=C++
+*.cxx linguist-language=C++
+*.h linguist-language=C
+*.hpp linguist-language=C++
+*.hxx linguist-language=C++
 
+# Keep the bar on library languages (helpers / legacy IDE / docs /
+# CMakeLists.txt config; leave *.cmake detectable as CMake)
+*.cmd -linguist-detectable
+*.dsp -linguist-detectable
+*.dsw -linguist-detectable
+*.html -linguist-detectable
+*.sh -linguist-detectable
+*.sln -linguist-detectable
+*.vcxproj -linguist-detectable
+*.vimrc -linguist-detectable
+CMakeLists.txt -linguist-detectable
+makefile -linguist-detectable
@@ -0,0 +1,109 @@
+name: Install Synesis dependencies
+description: >-
+  Clones, builds, and installs the named Synesis Information Systems
+  dependencies into a single CMake prefix, and exports that prefix both as
+  the SIS_DEPS environment variable and as the `prefix` output.
+
+inputs:
+  build-type:
+    description: CMake build type, for single-configuration generators
+    required: false
+    default: Release
+  c-compiler:
+    description: C compiler name, or the selector `cl`
+    required: true
+  cpp-compiler:
+    description: C++ compiler name; unused for the `cl` selector
+    required: true
+  dependencies:
+    description: >-
+      Whitespace-separated synesissoftware repository names, in dependency
+      order. Each is configured against those already installed, so this
+      list is deliberately NOT in lexicographic order.
+    required: true
+  install-prefix:
+    description: Directory into which every dependency is installed
+    required: false
+    default: ''
+  toolchain:
+    description: >-
+      Toolchain selector, for a toolchain that is not implied by the compiler
+      names and needs its own generator; presently only `mingw`. Empty
+      otherwise, in which case the compiler names alone select the toolchain.
+    required: false
+    default: ''
+
+outputs:
+  prefix:
+    description: Directory into which every dependency was installed
+    value: ${{ steps.install.outputs.prefix }}
+
+runs:
+  using: composite
+
+  steps:
+    - id: install
+      shell: bash
+      run: |
+        set -euo pipefail
+
+        PREFIX="${{ inputs.install-prefix }}"
+        [ -n "$PREFIX" ] || PREFIX="${RUNNER_TEMP}/sis-deps"
+
+        mkdir -p "$PREFIX"
+
+        if [ "${{ inputs.toolchain }}" = "mingw" ]; then
+          export PATH="/mingw64/bin:$PATH"
+        fi
+
+        for dep in ${{ inputs.dependencies }}; do
+
+          echo "::group::Installing $dep"
+
+          SRC="${RUNNER_TEMP}/${dep}-src"
+          BUILD="${RUNNER_TEMP}/${dep}-build"
+
+          git clone --depth 1 "https://github.com/synesissoftware/${dep}" "$SRC"
+
+          # NOTE: the generator and the build-type/compiler options are the
+          # *only* things that may differ between these paths; every other
+          # -D option is passed in all cases, so that no branch can silently
+          # ignore one.
+          if [ "${{ inputs.c-compiler }}" = "cl" ]; then
+            cmake -S "$SRC" -B "$BUILD" \
+              -DBUILD_EXAMPLES=OFF \
+              -DBUILD_TESTING=OFF \
+              -DCMAKE_DISABLE_FIND_PACKAGE_MFC=TRUE \
+              -DCMAKE_INSTALL_PREFIX="$PREFIX" \
+              -DCMAKE_PREFIX_PATH="$PREFIX"
+            cmake --build "$BUILD" --config "${{ inputs.build-type }}" --parallel
+            cmake --install "$BUILD" --config "${{ inputs.build-type }}"
+          elif [ "${{ inputs.toolchain }}" = "mingw" ]; then
+            cmake -S "$SRC" -B "$BUILD" -G "MinGW Makefiles" \
+              -DBUILD_EXAMPLES=OFF \
+              -DBUILD_TESTING=OFF \
+              -DCMAKE_BUILD_TYPE="${{ inputs.build-type }}" \
+              -DCMAKE_C_COMPILER="${{ inputs.c-compiler }}" \
+              -DCMAKE_CXX_COMPILER="${{ inputs.cpp-compiler }}" \
+              -DCMAKE_INSTALL_PREFIX="$PREFIX" \
+              -DCMAKE_PREFIX_PATH="$PREFIX"
+            cmake --build "$BUILD" --parallel 2
+            cmake --install "$BUILD"
+          else
+            cmake -S "$SRC" -B "$BUILD" \
+              -DBUILD_EXAMPLES=OFF \
+              -DBUILD_TESTING=OFF \
+              -DCMAKE_BUILD_TYPE="${{ inputs.build-type }}" \
+              -DCMAKE_C_COMPILER="${{ inputs.c-compiler }}" \
+              -DCMAKE_CXX_COMPILER="${{ inputs.cpp-compiler }}" \
+              -DCMAKE_INSTALL_PREFIX="$PREFIX" \
+              -DCMAKE_PREFIX_PATH="$PREFIX"
+            cmake --build "$BUILD" --parallel
+            cmake --install "$BUILD"
+          fi
+
+          echo "::endgroup::"
+        done
+
+        echo "prefix=$PREFIX" >> "$GITHUB_OUTPUT"
+        echo "SIS_DEPS=$PREFIX" >> "$GITHUB_ENV"