diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ce505a31f3..398e86793d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -50,8 +50,7 @@ jobs:
             desktop:
               - 'scripts/check-file-sizes-core.mjs'
               - 'scripts/check-file-sizes-core.test.mjs'
-              - 'desktop/**'
-              - '!desktop/src-tauri/**'
+              - 'desktop/!(src-tauri)/**'
               - 'pnpm-lock.yaml'
             desktop-rust:
               - 'desktop/src-tauri/**'
@@ -88,6 +87,8 @@ jobs:
         run: scripts/test-mobile-worktree-overrides.sh
       - name: File size ratchet unit tests
         run: node --test scripts/check-file-sizes-core.test.mjs
+      - name: CI path filter contract
+        run: node --test scripts/ci-path-filters.test.mjs
 
   rust-lint:
     name: Rust Lint
diff --git a/docs/ci-desktop-path-filter.md b/docs/ci-desktop-path-filter.md
new file mode 100644
index 0000000000..e10985d343
--- /dev/null
+++ b/docs/ci-desktop-path-filter.md
@@ -0,0 +1,84 @@
+# CI Desktop path-filter remediation
+
+## Status
+
+Implemented with TDD on `fix/ci-desktop-path-filter` from `origin/main`
+commit `0f7edef101f2`. Beads item `ios-buzz-59e.8` tracks delivery.
+
+## Root cause
+
+The CI workflow used these Desktop rules while the pinned
+`dorny/paths-filter` action retained its default
+`predicate-quantifier: some` behavior:
+
+```yaml
+desktop:
+  - 'desktop/**'
+  - '!desktop/src-tauri/**'
+```
+
+Under `some`, every rule is an independent predicate. The negative rule is
+true for every file outside `desktop/src-tauri`, so mobile, documentation, and
+Beads-only pull requests incorrectly produced `desktop=true`. That activated
+the Desktop matrix, including its GitHub-hosted macOS job. The unexpected run
+was cancelled immediately after the overmatch was confirmed.
+
+## Remediation
+
+The two-rule include/exclude combination is replaced with one positive
+picomatch extglob:
+
+```yaml
+desktop:
+  - 'desktop/!(src-tauri)/**'
+```
+
+This continues to classify Desktop frontend files and top-level Desktop files
+as `desktop=true`, while `desktop/src-tauri/**` remains exclusively classified
+by the existing `desktop-rust` filter. Existing downstream job conditions
+already accept either output, so Tauri validation coverage is unchanged.
+
+The regression contract is executed in the existing Ubuntu-based
+`Detect Changed Paths` job. It uses no new dependency and verifies:
+
+- mobile, documentation, and Beads files do not select Desktop;
+- Desktop frontend and top-level files do select Desktop;
+- `desktop/src-tauri` selects `desktop-rust`, not `desktop`;
+- the Desktop filter cannot reintroduce a standalone negative rule while the
+  action uses `some` semantics.
+
+## TDD evidence
+
+Red on untouched `origin/main`:
+
+- 3 contract tests failed;
+- a mobile file selected Desktop;
+- a Tauri file selected both Desktop filters; and
+- the standalone negative rule was detected.
+
+Green after the one-rule correction:
+
+- 3/3 new routing contracts passed;
+- all 6 existing file-size contract tests passed;
+- every existing contract command in the `Detect Changed Paths` job passed;
+- workflow YAML parsed successfully;
+- Biome and `git diff --check` passed; and
+- the replacement pattern matched the pinned action's picomatch semantics.
+
+## Delivery boundary
+
+Repository policy prohibits agents from starting GitHub-hosted macOS or
+Windows jobs. Because changing `.github/workflows/ci.yml` is itself classified
+as Rust/mobile work on current `main`, an agent-created pull request would
+start both hosted job families before this correction could take effect.
+
+The safe automated boundary is therefore a committed and pushed task branch
+without an agent-created pull request. A human must create and merge that CI
+pull request. Afterward, the iOS presence pull request can be refreshed and
+will classify its mobile/docs/Beads-only diff without starting hosted macOS or
+Windows jobs.
+
+## Rollback
+
+Revert the CI-filter commit. No application, relay, Desktop runtime, Hermes,
+certificate, or mobile rollback is required.
diff --git a/scripts/ci-path-filters.test.mjs b/scripts/ci-path-filters.test.mjs
new file mode 100644
index 0000000000..f9a23c131d
--- /dev/null
+++ b/scripts/ci-path-filters.test.mjs
@@ -0,0 +1,121 @@
+import assert from "node:assert/strict";
+import { readFileSync } from "node:fs";
+import test from "node:test";
+
+const workflow = readFileSync(
+  new URL("../.github/workflows/ci.yml", import.meta.url),
+  "utf8",
+);
+const filters = extractPathFilters(workflow);
+
+test("mobile, documentation, and Beads changes do not select Desktop", () => {
+  for (const file of [
+    "mobile/lib/features/profile/presence_cache_provider.dart",
+    "docs/ios-peer-presence-hydration.md",
+    ".beads/issues.jsonl",
+  ]) {
+    assert.equal(
+      matchesFilter(file, filters.desktop),
+      false,
+      `${file} must not select the Desktop filter`,
+    );
+  }
+});
+
+test("Desktop frontend and Tauri paths remain independently classified", () => {
+  assert.equal(matchesFilter("desktop/src/main.tsx", filters.desktop), true);
+  assert.equal(
+    matchesFilter("desktop/src-tauri/src/main.rs", filters.desktop),
+    false,
+  );
+  assert.equal(
+    matchesFilter("desktop/src-tauri/src/main.rs", filters["desktop-rust"]),
+    true,
+  );
+  assert.equal(matchesFilter("pnpm-lock.yaml", filters.desktop), true);
+});
+
+test("Desktop filter has no standalone negative rule under some semantics", () => {
+  assert.equal(
+    filters.desktop.some((pattern) => pattern.startsWith("!")),
+    false,
+    "a standalone negative rule matches every unrelated file when the action uses predicate-quantifier: some",
+  );
+});
+
+function extractPathFilters(source) {
+  const lines = source.split("\n");
+  const filtersMarker = lines.findIndex((line) => line.trim() === "filters: |");
+  assert.notEqual(filtersMarker, -1, "CI workflow must configure path filters");
+
+  const markerIndent = indentation(lines[filtersMarker]);
+  const filterIndent = markerIndent + 2;
+  const ruleIndent = filterIndent + 2;
+  const parsed = {};
+  let currentFilter;
+
+  for (const line of lines.slice(filtersMarker + 1)) {
+    if (line.trim() === "") continue;
+    const indent = indentation(line);
+    if (indent <= markerIndent) break;
+
+    if (indent === filterIndent) {
+      const match = line.trim().match(/^([a-z][a-z-]*):$/);
+      assert.ok(match, `invalid path filter declaration: ${line.trim()}`);
+      currentFilter = match[1];
+      parsed[currentFilter] = [];
+      continue;
+    }
+
+    if (indent === ruleIndent && currentFilter !== undefined) {
+      const match = line.trim().match(/^- '([^']+)'$/);
+      assert.ok(match, `invalid path filter rule: ${line.trim()}`);
+      parsed[currentFilter].push(match[1]);
+      continue;
+    }
+
+    assert.fail(`unexpected path filter syntax: ${line.trim()}`);
+  }
+
+  assert.ok(parsed.desktop, "Desktop path filter must exist");
+  assert.ok(parsed["desktop-rust"], "Desktop Rust path filter must exist");
+  return parsed;
+}
+
+function matchesFilter(file, patterns) {
+  return patterns.some((pattern) => matchesPattern(file, pattern));
+}
+
+function matchesPattern(file, pattern) {
+  if (pattern.startsWith("!")) {
+    return !matchesPositivePattern(file, pattern.slice(1));
+  }
+  return matchesPositivePattern(file, pattern);
+}
+
+function matchesPositivePattern(file, pattern) {
+  const negativeSegment = pattern.match(/^(.+)\/!\(([^)]+)\)\/\*\*$/);
+  if (negativeSegment !== null) {
+    const prefix = `${negativeSegment[1]}/`;
+    if (!file.startsWith(prefix)) return false;
+    const firstSegment = file.slice(prefix.length).split("/", 1)[0];
+    const excluded = negativeSegment[2].split("|");
+    return firstSegment.length > 0 && !excluded.includes(firstSegment);
+  }
+
+  if (pattern.endsWith("/**")) {
+    const prefix = pattern.slice(0, -3);
+    return file === prefix || file.startsWith(`${prefix}/`);
+  }
+
+  assert.equal(
+    pattern.includes("*"),
+    false,
+    `contract matcher does not support pattern: ${pattern}`,
+  );
+  return file === pattern;
+}
+
+function indentation(line) {
+  return line.length - line.trimStart().length;
+}