diff --git a/.claude/CLAUDE.md b/.claude/CLAUDE.md
index 60448c8a13..2cc82d5a06 100644
--- a/.claude/CLAUDE.md
+++ b/.claude/CLAUDE.md
@@ -66,6 +66,23 @@ Set `CommunityShadersOutputDir` environment variable to semicolon-separated Skyr
 CommunityShadersOutputDir=F:/MySkyrimModpack/mods/CommunityShaders;F:/SteamLibrary/steamapps/common/SkyrimVR/Data;F:/SteamLibrary/steamapps/common/Skyrim Special Edition/Data
 ```
 
+### IDE / clangd setup
+
+The shipped presets use the Visual Studio generator, which does **not** emit a
+`compile_commands.json`. Without one, clangd parses every TU with the fallback
+flags in `.clangd` and reports false "unknown include / undefined symbol"
+diagnostics. After configuring the `ALL` preset once, generate an accurate
+compile database:
+
+```bash
+pwsh tools/gen-clangd-db.ps1
+```
+
+It stands up a throwaway Ninja configure (no build, reuses the `ALL` preset's
+vcpkg packages), writes `compile_commands.json` to the repo root (gitignored,
+machine-specific), and rewrites paths when the build runs under a `subst` drive.
+Re-run it when the include graph or CMake options change, then restart clangd.
+
 ### Shader Development and Testing
 
 ```bash
@@ -561,6 +578,15 @@ After a hotfix release, open PRs targeting `dev` are auto-rebased by the `Auto-r
 
 Full details: [Open Shaders developer wiki — Patch Release Process](https://github.com/alandtse/open-shaders/wiki/Developers#patch-release-process-any-line). The fork now maintains its own wiki (transferred from upstream) at `alandtse/open-shaders/wiki`; the `maint-update-wiki.yaml` workflow auto-publishes buffer documentation there on every push to `dev`. Upstream Community Shaders maintains its own copy at `community-shaders/skyrim-community-shaders/wiki` — link to whichever is appropriate for the audience.
 
+### Syncing from upstream Community Shaders
+
+Upstream is `community-shaders/skyrim-community-shaders`. Pull its changes **by merge, never cherry-pick** — this is the rule that keeps future syncs cheap:
+
+-   **Merge, don't cherry-pick.** `git merge <upstream-ref>` (an upstream `vX.Y.Z` tag — there is no `upstream/master`). Cherry-pick rewrites each commit to a new SHA, so upstream's originals never become ancestors and the **next** `git merge` re-conflicts on the same hunks forever. A merge makes the upstream commits ancestors once, so subsequent syncs are clean.
+-   **Land the sync PR as a merge commit, never squash.** Squash collapses the merge into one fresh SHA and throws the ancestry away, undoing the whole point. The repo default is squash, so the PR must be set to "Create a merge commit" explicitly (mirrors the #121 sync).
+-   **Verify ancestry after landing:** `git merge-base --is-ancestor <upstream-sha> HEAD` must pass for each adopted upstream commit.
+-   **Resolve conflicts in favor of keeping VR** (this fork is the VR maintainer). Typical conflicts are just fork CI config or feature `.ini` versions — resolve `--ours`. If upstream ships a VR removal, revert it and keep VR.
+
 ### Code Organization and Refactoring Patterns
 
 -   **Extract Large Functions**: Functions over ~200 lines should be broken into focused helper methods (see `FeatureListRenderer::DrawMenuVisitor` refactoring)
diff --git a/.gitignore b/.gitignore
index 6637671cd0..72497669e5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -17,3 +17,7 @@ tests/shaders/*.exe
 tests/shaders/*.pdb
 tests/shaders/Shaders/
 tools/__pycache__/
+
+# clangd compile database (machine-specific absolute paths; regenerate with
+# tools/gen-clangd-db.ps1)
+/compile_commands.json
diff --git a/tools/gen-clangd-db.ps1 b/tools/gen-clangd-db.ps1
new file mode 100644
index 0000000000..ead54f6c68
--- /dev/null
+++ b/tools/gen-clangd-db.ps1
@@ -0,0 +1,121 @@
+#requires -Version 5.1
+<#
+.SYNOPSIS
+  Generate a clangd compile_commands.json for this checkout.
+
+.DESCRIPTION
+  The shipped CMake presets use the Visual Studio generator, which does NOT emit
+  compile_commands.json (only Ninja/Makefile generators do). Without a real
+  compile DB, clangd parses every TU with the hand-maintained fallback flags in
+  .clangd and floods the editor with false "unknown include / undefined symbol"
+  diagnostics. This script stands up a throwaway Ninja configure (no build) purely
+  to emit an accurate DB, then drops it at the repo root where clangd
+  auto-discovers it.
+
+  It reuses the vcpkg packages already installed by the -ReuseVcpkgFrom build dir
+  (default build/ALL), so it does not re-run a vcpkg install. Configure that
+  preset once before running this.
+
+  MAX_PATH note: long checkout paths blow MAX_PATH for the FidelityFX/vcpkg
+  permutation headers, so some setups build under a `subst` drive. If a subst
+  drive maps to this checkout, the script builds under it and rewrites the
+  emitted DB paths back to the real checkout path (clangd opens files via the
+  real path, so the DB must match). With no subst drive it builds in-place.
+
+  Re-run after any change that alters the include graph or defines (new source
+  file, new feature dir, CMake option flip).
+
+.EXAMPLE
+  pwsh tools/gen-clangd-db.ps1
+#>
+[CmdletBinding()]
+param(
+    # Build dir whose installed vcpkg packages are reused (so this does not
+    # re-run a full vcpkg install). Configure this preset first.
+    [string]$ReuseVcpkgFrom = 'build/ALL'
+)
+$ErrorActionPreference = 'Stop'
+
+$root = (& git -C $PSScriptRoot rev-parse --show-toplevel).Trim()
+if (-not $root) { throw 'Not inside a git checkout' }
+$rootFwd = ($root -replace '\\', '/').TrimEnd('/')
+
+# Build under a subst drive if one maps to this checkout (MAX_PATH workaround);
+# otherwise build in-place at the repo root.
+$drive = $null
+foreach ($line in (subst)) {
+    # `subst` prints "Z:\: => C:\path"; tolerate the trailing colon and an
+    # optional backslash so the mapped-drive lookup actually matches.
+    if ($line -match '^([A-Z]):\\?:?\s*=>\s*(.+)$') {
+        if ($matches[2].TrimEnd('\') -ieq $root.TrimEnd('\')) { $drive = "$($matches[1]):"; break }
+    }
+}
+$base = if ($drive) { $drive } else { $rootFwd }
+Write-Host "Checkout : $root"
+Write-Host "Build at : $base$(if ($drive) { '  (subst drive; paths rewritten back)' })"
+
+# Discover the MSVC dev environment. Ninja needs cl on PATH; the VS generator
+# sets this up implicitly, Ninja does not. -prerelease covers Insiders installs
+# and is harmless on stable-only machines.
+$vswhere = "${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe"
+if (-not (Test-Path $vswhere)) { throw "vswhere.exe not found at $vswhere" }
+$vsRoot = (& $vswhere -latest -prerelease -property installationPath | Select-Object -First 1).Trim()
+if (-not $vsRoot) { throw 'vswhere found no Visual Studio install (need the Desktop development with C++ workload).' }
+$vcvars = Join-Path $vsRoot 'VC\Auxiliary\Build\vcvars64.bat'
+if (-not (Test-Path $vcvars)) { throw "vcvars64.bat not found under $vsRoot" }
+cmd /c "`"$vcvars`" && set" | ForEach-Object {
+    if ($_ -match '^([^=]+)=(.*)$') { Set-Item -Path "env:$($matches[1])" -Value $matches[2] }
+}
+if (-not (Get-Command cl -ErrorAction SilentlyContinue)) { throw 'cl not on PATH after vcvars import' }
+
+# Read the vcpkg toolchain + triplet from the existing cache so we match the real
+# build instead of hardcoding paths.
+$cache = Join-Path $root "$ReuseVcpkgFrom/CMakeCache.txt"
+if (-not (Test-Path $cache)) { throw "No CMakeCache at $cache - configure the $ReuseVcpkgFrom preset first" }
+$cacheText = Get-Content $cache -Raw
+$toolchain = ([regex]'CMAKE_TOOLCHAIN_FILE(?::\w+)?=(.+)').Match($cacheText).Groups[1].Value.Trim()
+$triplet   = ([regex]'VCPKG_TARGET_TRIPLET(?::\w+)?=(.+)').Match($cacheText).Groups[1].Value.Trim()
+if (-not $toolchain) { throw "Could not read CMAKE_TOOLCHAIN_FILE from $cache" }
+if (-not $triplet)   { $triplet = 'x64-windows-static-md' }
+
+$genDir   = "$base/build/clangd-gen"
+$vcpkgDir = "$base/$ReuseVcpkgFrom/vcpkg_installed"
+
+# Configure-only (no build) under Ninja to emit the DB. /machine:x64 satisfies
+# FidelityFX-SDK's platform check, which keys off the VS -A arch that Ninja
+# doesn't set. Flags mirror the ALL preset (all three runtimes).
+$cmakeArgs = @(
+    '-S', "$base/", '-B', $genDir, '-G', 'Ninja',
+    '-DCMAKE_BUILD_TYPE=Release',
+    '-DCMAKE_EXPORT_COMPILE_COMMANDS=ON',
+    '-DCMAKE_EXE_LINKER_FLAGS=/machine:x64',
+    "-DCMAKE_TOOLCHAIN_FILE=$toolchain",
+    "-DVCPKG_OVERLAY_PORTS=$base/cmake/ports/",
+    "-DVCPKG_TARGET_TRIPLET=$triplet",
+    "-DVCPKG_INSTALLED_DIR=$vcpkgDir",
+    '-DVCPKG_MANIFEST_INSTALL=OFF',
+    '-DCMAKE_MSVC_RUNTIME_LIBRARY=MultiThreadedDLL',
+    '-DSKSE_SUPPORT_XBYAK=ON',
+    '-DENABLE_SKYRIM_AE=ON', '-DENABLE_SKYRIM_SE=ON', '-DENABLE_SKYRIM_VR=ON',
+    '-DAUTO_PLUGIN_DEPLOYMENT=OFF',
+    '-DCOMMONLIB_PREBUILT_MULTICONFIG=ON',
+    '-DBUILD_CPP_TESTS=OFF'
+)
+Write-Host 'Configuring Ninja DB (no build)...'
+# Let cmake's diagnostics reach the console and check its native exit code —
+# $ErrorActionPreference='Stop' does not trip on a non-zero exe exit, so a
+# silent configure failure would otherwise surface only as the generic
+# "did not produce compile_commands.json" below.
+& cmake @cmakeArgs
+if ($LASTEXITCODE -ne 0) { throw "cmake configure failed (exit code $LASTEXITCODE)." }
+$dbSrc = Join-Path $root 'build/clangd-gen/compile_commands.json'
+if (-not (Test-Path $dbSrc)) { throw 'Configure did not produce compile_commands.json' }
+
+# Drop the DB at repo root. When built under a subst drive, rewrite that drive
+# root back to the real checkout path so clangd's file lookups match.
+$text = [System.IO.File]::ReadAllText($dbSrc)
+if ($drive) { $text = $text.Replace($drive, $rootFwd) }
+$dest = Join-Path $root 'compile_commands.json'
+[System.IO.File]::WriteAllText($dest, $text, (New-Object System.Text.UTF8Encoding($false)))
+$count = ([regex]'"file":').Matches($text).Count
+Write-Host "Wrote $dest ($count entries). Restart clangd to pick it up."