diff --git a/nix/desktop-package.nix b/nix/desktop-package.nix
index 9703c497ae..cd9c6ca5c2 100644
--- a/nix/desktop-package.nix
+++ b/nix/desktop-package.nix
@@ -33,6 +33,21 @@ buildNpmPackage rec {
       && !(lib.hasPrefix "/packages/app/ios" relPath)
       # Website is unrelated to the desktop app
       && !(lib.hasPrefix "/packages/website" relPath)
+      # Documentation, CI definitions and agent/editor configuration. None of
+      # these reach the build, but every one of them is part of `src`, so a
+      # docs-only or workflow-only commit currently invalidates the whole
+      # desktop derivation and pays for a full Expo export to produce a
+      # byte-identical result.
+      && !(lib.hasPrefix "/docs" relPath)
+      && !(lib.hasPrefix "/.github" relPath)
+      && !(lib.hasPrefix "/.agents" relPath)
+      && !(lib.hasPrefix "/.claude" relPath)
+      && !(lib.hasPrefix "/.codex" relPath)
+      && !(lib.hasPrefix "/docker" relPath)
+      # Top-level prose only (README, CHANGELOG, AGENTS...). Deeper markdown is
+      # not necessarily documentation: skills/*/SKILL.md is a runtime file the
+      # installPhase copies into the output.
+      && builtins.match "/[^/]+\\.md" relPath == null
       # Test fixtures and build artifacts
       && !(lib.hasSuffix ".test.ts" baseName)
       && !(lib.hasSuffix ".e2e.test.ts" baseName)
diff --git a/nix/package.nix b/nix/package.nix
index b30665b8c9..417f3d2ad1 100644
--- a/nix/package.nix
+++ b/nix/package.nix
@@ -37,6 +37,21 @@ buildNpmPackage rec {
       && !(lib.hasPrefix "/packages/website/public" relPath)
       && !(lib.hasPrefix "/packages/desktop/src" relPath)
       && !(lib.hasPrefix "/packages/desktop/src-tauri" relPath)
+      # Documentation, CI definitions and agent/editor configuration. None of
+      # these reach the build. Excluding them here also matters for the desktop
+      # derivation, which inherits this package's npmDeps: leaving them in makes
+      # a docs-only commit produce a new npm-deps .drv, and so a new desktop
+      # .drv, and so a full rebuild for a byte-identical result.
+      && !(lib.hasPrefix "/docs" relPath)
+      && !(lib.hasPrefix "/.github" relPath)
+      && !(lib.hasPrefix "/.agents" relPath)
+      && !(lib.hasPrefix "/.claude" relPath)
+      && !(lib.hasPrefix "/.codex" relPath)
+      && !(lib.hasPrefix "/docker" relPath)
+      # Top-level prose only (README, CHANGELOG, AGENTS...). Deeper markdown is
+      # not necessarily documentation: skills/*/SKILL.md is a runtime file the
+      # daemon's trace script copies into the output.
+      && builtins.match "/[^/]+\\.md" relPath == null
       # Exclude test fixtures and debug files
       && !(lib.hasSuffix ".test.ts" baseName)
       && !(lib.hasSuffix ".e2e.test.ts" baseName)