diff --git a/bin/gstack-gbrain-install b/bin/gstack-gbrain-install
index 84091c236..e27d0ab7d 100755
--- a/bin/gstack-gbrain-install
+++ b/bin/gstack-gbrain-install
@@ -96,6 +96,19 @@ if ! $VALIDATE_ONLY; then
   fi
 fi
 
+# Read a string field (dotted path, e.g. bin.gbrain) from a package.json with
+# bun, which this installer already requires. It used to need jq, which it
+# never checked for, so a successful install reported failure (#1675).
+pkg_field() {
+  GSTACK_PKG_JSON="$1" GSTACK_PKG_FIELD="$2" bun -e '
+    try {
+      const pkg = JSON.parse(require("fs").readFileSync(process.env.GSTACK_PKG_JSON, "utf8"));
+      const v = process.env.GSTACK_PKG_FIELD.split(".").reduce((o, k) => (o == null ? o : o[k]), pkg);
+      if (typeof v === "string") process.stdout.write(v);
+    } catch {}
+  ' 2>/dev/null || true
+}
+
 # --- D5 detect-first: probe common locations before cloning fresh ---
 # Accept any directory that looks like a gbrain clone: has package.json
 # with name "gbrain" and a `bin.gbrain` entry. Don't accept version mismatches
@@ -105,10 +118,10 @@ is_valid_clone() {
   [ -d "$dir" ] || return 1
   [ -f "$dir/package.json" ] || return 1
   local name
-  name=$(jq -r '.name // empty' "$dir/package.json" 2>/dev/null || true)
+  name=$(pkg_field "$dir/package.json" name)
   [ "$name" = "gbrain" ] || return 1
   local bin
-  bin=$(jq -r '.bin.gbrain // empty' "$dir/package.json" 2>/dev/null || true)
+  bin=$(pkg_field "$dir/package.json" bin.gbrain)
   [ -n "$bin" ] || return 1
   return 0
 }
@@ -199,7 +212,7 @@ _bun_exe_hint() {
 # Read the version from the install-dir's package.json; compare to
 # `gbrain --version`. If they disagree, PATH is returning a DIFFERENT
 # gbrain than the one we just linked. Fail hard with remediation.
-expected_version=$(jq -r '.version // empty' "$INSTALL_DIR/package.json" 2>/dev/null || true)
+expected_version=$(pkg_field "$INSTALL_DIR/package.json" version)
 if [ -z "$expected_version" ]; then
   fail "cannot read version from $INSTALL_DIR/package.json (install may be broken)"
 fi
diff --git a/bin/gstack-gbrain-source-wireup b/bin/gstack-gbrain-source-wireup
index 05e50b1df..7b9ace1b6 100755
--- a/bin/gstack-gbrain-source-wireup
+++ b/bin/gstack-gbrain-source-wireup
@@ -36,7 +36,7 @@
 # at src/core/config.ts:53), so a process that flips config.json mid-sync
 # can't redirect us at a different brain mid-stream.
 #
-# Depends on: jq (transitive via gstack-gbrain-detect).
+# Depends on: bun (already a gstack dependency), gbrain, git.
 
 set -euo pipefail
 
@@ -204,21 +204,34 @@ ensure_worktree() {
 }
 
 # ---- gbrain sources operations ----
+# Read .sources[] | select(.id==$id) | .local_path out of `gbrain sources list`
+# with bun (a gstack dependency). This used to need jq, which nothing installs
+# and which git-bash on Windows lacks, so the wireup was skipped every run
+# (#2369). Prints the path, or nothing when the id is absent or the payload
+# is not JSON.
+source_local_path() {
+  gbrain sources list --json 2>/dev/null \
+    | GB_SOURCE_ID="$1" bun -e '
+        const raw = await Bun.stdin.text();
+        try {
+          const s = (JSON.parse(raw).sources || []).find((x) => x.id === process.env.GB_SOURCE_ID);
+          process.stdout.write(s?.local_path ?? "");
+        } catch {}
+      ' 2>/dev/null \
+    | tr -d '[:space:]'
+}
+
 # Returns 0 if source with id exists at expected path. 1 if exists but path differs. 2 if absent.
-# Hard-fails (exits non-zero via die) if jq is missing — without jq we cannot
-# distinguish "absent" from "missing-tool" and would falsely re-add an existing
-# source. jq is documented as a dependency of gstack-gbrain-detect (transitive)
-# but adversarial review flagged the silent-fall-through path; this probe makes
-# the failure mode loud.
+# Hard-fails (exits non-zero via die) if the JSON reader is unavailable: we
+# could not then tell "absent" from "missing tool" and would falsely re-add an
+# existing source.
 check_source_state() {
   local id="$1"
-  if ! command -v jq >/dev/null 2>&1; then
-    die "jq required for source state detection. Install jq (brew install jq) and re-run." 1
+  if ! command -v bun >/dev/null 2>&1; then
+    die "bun required for source state detection. Install bun (https://bun.sh) and re-run." 1
   fi
   local existing_path
-  existing_path=$(gbrain sources list --json 2>/dev/null \
-    | jq -r --arg id "$id" '.sources[] | select(.id==$id) | .local_path' 2>/dev/null \
-    | tr -d '[:space:]') || existing_path=""
+  existing_path=$(source_local_path "$id") || existing_path=""
   if [ -z "$existing_path" ]; then
     return 2
   fi
@@ -299,9 +312,7 @@ do_wireup() {
       # registration. Just sync from our local worktree — gbrain stores pages
       # by content, not by local_path. The metadata is informational only.
       local existing_path
-      existing_path=$(gbrain sources list --json 2>/dev/null \
-        | jq -r --arg id "$id" '.sources[] | select(.id==$id) | .local_path' 2>/dev/null \
-        | tr -d '[:space:]') || existing_path=""
+      existing_path=$(source_local_path "$id") || existing_path=""
       if [ "$(basename "$existing_path")" = "$(basename "$WORKTREE")" ] \
          && [ "$existing_path" != "$WORKTREE" ]; then
         warn "source $id is registered at $existing_path (likely another machine's local copy of the same brain repo). Skipping re-registration; will sync from local worktree."
diff --git a/test/gbrain-detect-install.test.ts b/test/gbrain-detect-install.test.ts
index c234d3a2d..34ff1803d 100644
--- a/test/gbrain-detect-install.test.ts
+++ b/test/gbrain-detect-install.test.ts
@@ -324,3 +324,39 @@ describe('gstack-gbrain-install argument handling', () => {
     expect(r.stderr).toContain('unknown flag');
   });
 });
+
+// B8 (#1675): the installer reads package.json with bun; it used to need jq,
+// never checked for it, and reported a successful install as failed.
+describe('gstack-gbrain-install without jq (B8)', () => {
+  function pathWithoutJq(extra: string): string {
+    const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'no-jq-bin-'));
+    for (const base of ['/usr/bin', '/bin', '/usr/sbin', '/sbin']) {
+      if (!fs.existsSync(base)) continue;
+      for (const name of fs.readdirSync(base)) {
+        if (name === 'jq' || name === 'gbrain' || fs.existsSync(path.join(dir, name))) continue;
+        try { fs.symlinkSync(path.join(base, name), path.join(dir, name)); } catch {}
+      }
+    }
+    return `${extra}:${dir}:${BUN_ONLY_DIR}`;
+  }
+
+  test('validates a matching install and reuses a detected clone with no jq on PATH', async () => {
+    const installDir = path.join(tmpHomeReal, 'gbrain-install');
+    fs.mkdirSync(installDir, { recursive: true });
+    fs.writeFileSync(path.join(installDir, 'package.json'), JSON.stringify({ name: 'gbrain', version: '0.60.37', bin: { gbrain: 'src/cli.ts' } }));
+    const fakeBin = fs.mkdtempSync(path.join(os.tmpdir(), 'fake-gbrain-'));
+    fs.writeFileSync(path.join(fakeBin, 'gbrain'), '#!/bin/sh\necho "gbrain 0.60.37"\n', { mode: 0o755 });
+    const PATH = pathWithoutJq(fakeBin);
+    const ok = await run(INSTALL, ['--validate-only', '--install-dir', installDir], { env: { PATH } });
+    expect(ok.stderr).not.toContain('cannot read version');
+    expect(ok.status).toBe(0);
+
+    const clone = path.join(tmpHomeReal, 'git', 'gbrain');
+    fs.mkdirSync(clone, { recursive: true });
+    fs.writeFileSync(path.join(clone, 'package.json'), JSON.stringify({ name: 'gbrain', version: '0.60.37', bin: { gbrain: 'src/cli.ts' } }));
+    const dry = await run(INSTALL, ['--dry-run'], { env: { PATH } });
+    expect(dry.stdout).toContain(`detected existing gbrain clone at ${clone}`);
+    fs.rmSync(fakeBin, { recursive: true, force: true });
+  });
+});
+
diff --git a/test/gstack-gbrain-source-wireup.test.ts b/test/gstack-gbrain-source-wireup.test.ts
index 4b7858c5f..2fc906441 100644
--- a/test/gstack-gbrain-source-wireup.test.ts
+++ b/test/gstack-gbrain-source-wireup.test.ts
@@ -565,3 +565,34 @@ describe('gstack-gbrain-source-wireup — defensive paths', () => {
     expect(fs.existsSync(path.join(worktreeDir, 'unrelated.txt'))).toBe(false); // stray gone
   });
 });
+
+// B8 (#2369): the wireup reads `gbrain sources list --json` with bun, so a
+// machine without jq (git-bash on Windows, minimal Linux) still wires up.
+describe('gstack-gbrain-source-wireup without jq (B8)', () => {
+  function pathWithoutJq(): string {
+    const dir = path.join(tmpHome, 'no-jq-bin');
+    fs.mkdirSync(dir, { recursive: true });
+    for (const base of ['/usr/bin', '/bin', '/usr/sbin', '/sbin']) {
+      if (!fs.existsSync(base)) continue;
+      for (const name of fs.readdirSync(base)) {
+        if (name === 'jq' || fs.existsSync(path.join(dir, name))) continue;
+        try { fs.symlinkSync(path.join(base, name), path.join(dir, name)); } catch {}
+      }
+    }
+    return `${fakeBinDir}:${dir}:${BUN_ONLY_DIR}`;
+  }
+
+  test('detects an already-registered source and re-runs cleanly with no jq on PATH', () => {
+    setupGstackRepo('git@github.com:user/gstack-brain-user.git');
+    makeFakeGbrain({});
+    const PATH = pathWithoutJq();
+    expect(spawnSync('sh', ['-c', 'command -v jq'], { env: { PATH }, timeout: 10_000 }).status).not.toBe(0);
+    const first = run([], { env: { PATH, GSTACK_BRAIN_NO_SYNC: '1' } });
+    expect(first.stderr).not.toContain('jq required');
+    expect(first.status).toBe(0);
+    const second = run([], { env: { PATH, GSTACK_BRAIN_NO_SYNC: '1' } });
+    expect(second.status).toBe(0);
+    expect(readState().sources).toHaveLength(1);
+  });
+});
+