diff --git a/CHANGELOG.md b/CHANGELOG.md
index 336bdf5c..fd5c54f5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1240,3 +1240,8 @@ First versioned/packaged release. Installable as a Claude Code **plugin** (`/plu
   section on an exclusive flock (#970). A dependency build longer than one
   tick no longer accumulates concurrent `start.sh`/`dependency_bootstrap`
   runs (cargo "Text file busy"); a tick that finds a start in flight skips.
+- Termux/Android Rust toolchain is now a setup-managed prerequisite (#968):
+  `setup.sh` installs `rust` + `rust-std-aarch64-linux-android` via `pkg` (or
+  fails loudly with the exact line), and `dependency_bootstrap.py` warns
+  upfront when cargo is absent and names it as the likely cause of a
+  hash-locked build failure instead of a maturin backtrace.
diff --git a/bridge/dependency_bootstrap.py b/bridge/dependency_bootstrap.py
index a57b6732..4f5a6249 100644
--- a/bridge/dependency_bootstrap.py
+++ b/bridge/dependency_bootstrap.py
@@ -161,6 +161,14 @@ def ensure_android_api_level(
         print(f"\033[90m✓ Android API level auto-detected: {sdk}\033[0m", file=stdout, flush=True)
 
 
+def _is_termux_env(env: Mapping[str, str]) -> bool:
+    return bool(env.get("TERMUX_VERSION")) or "/com.termux/" in env.get("PREFIX", "")
+
+
+def _cargo_available(env: Mapping[str, str]) -> bool:
+    return shutil.which("cargo", path=env.get("PATH")) is not None
+
+
 def _saved_fingerprint(path: Path) -> str:
     if not path.is_file():
         return ""
@@ -170,11 +178,22 @@ def _saved_fingerprint(path: Path) -> str:
         return ""
 
 
-def _print_install_failure(mode: InstallMode, command_index: int, stdout: TextIO) -> None:
+def _print_install_failure(
+    mode: InstallMode, command_index: int, stdout: TextIO, *, rust_missing: bool = False
+) -> None:
     if mode is InstallMode.LOCKED and command_index == 0:
         print("❌ Hash-locked dependency installation failed", file=stdout, flush=True)
-        print("   If this host cannot install a locked artifact, retry with", file=stdout)
-        print("   CCC_DEPS_UNLOCKED=1 and report the platform gap.", file=stdout)
+        if rust_missing:
+            # #968: on Android/Termux a missing toolchain, not the lock, is the
+            # usual killer — name it instead of a maturin/rustup backtrace.
+            print("   Likely cause: this Android/Termux host has no Rust toolchain,", file=stdout)
+            print("   so packages without an Android-compatible wheel cannot build", file=stdout)
+            print("   (maturin needs cargo). Fix and retry:", file=stdout)
+            print("   pkg install rust rust-std-aarch64-linux-android", file=stdout)
+            print("   CCC_DEPS_UNLOCKED=1 does NOT bypass a missing toolchain.", file=stdout)
+        else:
+            print("   If this host cannot install a locked artifact, retry with", file=stdout)
+            print("   CCC_DEPS_UNLOCKED=1 and report the platform gap.", file=stdout)
     elif mode is InstallMode.UNLOCKED and command_index == 0:
         print("❌ Failed to upgrade pip", file=stdout, flush=True)
     elif mode is InstallMode.UNLOCKED and command_index == 1:
@@ -206,6 +225,15 @@ def sync_dependencies(
     print("📦 Installing Python dependencies...", file=stdout, flush=True)
     child_env = dict(os.environ if environ is None else environ)
     ensure_android_api_level(child_env, stdout=stdout)
+    rust_missing = _is_termux_env(child_env) and not _cargo_available(child_env)
+    if rust_missing:
+        print(
+            "⚠️  Android/Termux host without a Rust toolchain — packages without "
+            "an Android-compatible wheel (e.g. cryptography via maturin) will fail "
+            "to build. Install it with: pkg install rust rust-std-aarch64-linux-android",
+            file=stdout,
+            flush=True,
+        )
     if mode is InstallMode.LOCKED and not paths.lock.is_file():
         print(f"❌ Hash lock not found: {paths.lock}", file=stdout)
         print("   Regenerate it with scripts/ccc-deps-lock.sh, or set", file=stdout)
@@ -226,7 +254,7 @@ def sync_dependencies(
             _print_install_failure(mode, index, stdout)
             return 1
         if result.returncode != 0:
-            _print_install_failure(mode, index, stdout)
+            _print_install_failure(mode, index, stdout, rust_missing=rust_missing)
             return 1
 
     try:
diff --git a/bridge/tests/test_deps_install_mode.py b/bridge/tests/test_deps_install_mode.py
index 01828fb7..9924937c 100644
--- a/bridge/tests/test_deps_install_mode.py
+++ b/bridge/tests/test_deps_install_mode.py
@@ -362,5 +362,81 @@ def test_operator_android_api_level_skips_getprop(self):
             self.assertIn("ANDROID_API_LEVEL=34", (Path(tmpdir) / "pip-calls.log").read_text())
 
 
+class RustToolchainPreflightTests(unittest.TestCase):
+    """#968: Android/Termux hash-locked installs need a Rust toolchain."""
+
+    def _make_paths(self, root: Path, pip_exit: int) -> DependencyPaths:
+        bridge = root / "bridge"
+        bin_dir = bridge / "venv" / "bin"
+        bin_dir.mkdir(parents=True, exist_ok=True)
+        requirements = bridge / "requirements.txt"
+        requirements.write_text("demo==1.0\n", encoding="utf-8")
+        lock = bridge / "requirements.lock.txt"
+        lock.write_text("demo==1.0 --hash=sha256:abc\n", encoding="utf-8")
+        pyproject = bridge / "pyproject.toml"
+        pyproject.write_text("[project]\nname = 'demo'\n", encoding="utf-8")
+        pip = bin_dir / "pip"
+        pip.write_text(f"#!/bin/bash\nexit {pip_exit}\n", encoding="utf-8")
+        pip.chmod(0o755)
+        return DependencyPaths(
+            bridge_dir=bridge,
+            venv_dir=bridge / "venv",
+            project_env=root / "project.env",
+            bridge_env=root / "bridge.env",
+            requirements=requirements,
+            lock=lock,
+            pyproject=pyproject,
+            hash_cache=bridge / ".req_hash",
+            pip=pip,
+        )
+
+    def _run(self, paths: DependencyPaths, *, pip_exit: int, cargo: bool):
+        import io
+
+        from telegram_bot.dependency_bootstrap import sync_dependencies
+
+        with tempfile.TemporaryDirectory() as tmpdir:
+            fake_bin = Path(tmpdir) / "bin"
+            fake_bin.mkdir()
+            if cargo:
+                cargo_bin = fake_bin / "cargo"
+                cargo_bin.write_text("#!/bin/bash\nexit 0\n", encoding="utf-8")
+                cargo_bin.chmod(0o755)
+            environ = {
+                "TERMUX_VERSION": "0.118",
+                "PATH": f"{fake_bin}{os.pathsep}/usr/bin{os.pathsep}/bin",
+            }
+            buf = io.StringIO()
+            rc = sync_dependencies(
+                paths, InstallMode.LOCKED, force_install=True, environ=environ, stdout=buf
+            )
+            return rc, buf.getvalue()
+
+    def test_termux_without_cargo_warns_upfront_and_diagnoses_failure(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            paths = self._make_paths(Path(tmpdir), pip_exit=1)
+            rc, out = self._run(paths, pip_exit=1, cargo=False)
+            self.assertEqual(rc, 1)
+            self.assertIn("without a Rust toolchain", out)
+            self.assertIn("pkg install rust rust-std-aarch64-linux-android", out)
+            self.assertIn("does NOT bypass a missing toolchain", out)
+            self.assertNotIn("report the platform gap", out)
+
+    def test_termux_with_cargo_keeps_legacy_hint_and_skips_warning(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            paths = self._make_paths(Path(tmpdir), pip_exit=1)
+            rc, out = self._run(paths, pip_exit=1, cargo=True)
+            self.assertEqual(rc, 1)
+            self.assertNotIn("without a Rust toolchain", out)
+            self.assertIn("CCC_DEPS_UNLOCKED=1 and report the platform gap.", out)
+
+    def test_termux_without_cargo_warns_but_does_not_block_success(self):
+        with tempfile.TemporaryDirectory() as tmpdir:
+            paths = self._make_paths(Path(tmpdir), pip_exit=0)
+            rc, out = self._run(paths, pip_exit=0, cargo=False)
+            self.assertEqual(rc, 0)
+            self.assertIn("without a Rust toolchain", out)
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/docs/android-termux-claude.md b/docs/android-termux-claude.md
index d1f1fc5d..e636b3bb 100644
--- a/docs/android-termux-claude.md
+++ b/docs/android-termux-claude.md
@@ -23,6 +23,21 @@ it from scratch.
   This repo (ccc-node) only needs the bridge-side tweaks noted below.
 - Avoid proot for the runtime: it works but is ~9x slower.
 
+## Bridge dependency builds: Rust toolchain is a hard prerequisite (#968)
+
+Hash-locked installs (`bridge/requirements.lock.txt`) may contain packages
+with **no Android wheel** — e.g. `cryptography` 50, which builds via maturin
+and therefore needs **Rust**. A missing toolchain killed the `daegyo` bridge
+on 2026-08-06 (restart -> lock reconcile -> maturin failure -> 4h15m outage);
+`gongyung` survived only because Rust was already present.
+
+- `setup.sh` now installs `rust` + `rust-std-aarch64-linux-android` via `pkg`
+  on Termux (or prints the exact install line when it cannot).
+- `dependency_bootstrap.py` warns upfront when an Android/Termux host lacks
+  cargo, and its install-failure message names the toolchain as the likely
+  cause. `CCC_DEPS_UNLOCKED=1` does **not** bypass a missing toolchain.
+- Manual fix: `pkg install rust rust-std-aarch64-linux-android`.
+
 ## Root cause — why glibc-native fails
 
 Symptom when launching the native node/claude binary:
diff --git a/scripts/setup.test.sh b/scripts/setup.test.sh
index 4794a75e..25529a6c 100644
--- a/scripts/setup.test.sh
+++ b/scripts/setup.test.sh
@@ -438,6 +438,30 @@ HOME="$lb_home" CCC_CLAUDE_DIR="$lb_claude" CCC_HERMES_DIR="$lb_hermes" \
   bash "$SETUP" --no-backup >/dev/null 2>&1
 ok "setup installs the versioned live-backups rotate script" \
   '[ -x "$lb_home/.ccc-node/scripts/ccc-live-backups-rotate.sh" ] && grep -q "CCC_LIVE_BACKUPS_ROOTS" "$lb_home/.ccc-node/scripts/ccc-live-backups-rotate.sh"'
+# #968: Termux Rust toolchain handling.
+tm_home="$TMP/tm-home"; tm_claude="$TMP/tm-claude"; tm_hermes="$TMP/tm-hermes"; tm_bin="$TMP/tm-bin"
+mkdir -p "$tm_bin"
+printf '#!/usr/bin/env bash\necho "$@" >> "%s"\nexit 0\n' "$TMP/tm-pkg.calls" > "$tm_bin/pkg"
+chmod +x "$tm_bin/pkg"
+out="$(HOME="$tm_home" CCC_CLAUDE_DIR="$tm_claude" CCC_HERMES_DIR="$tm_hermes" \
+  TERMUX_VERSION=0.118 PATH="$tm_bin:/usr/local/bin:/usr/bin:/bin" bash "$SETUP" --no-backup 2>&1)"; rc=$?
+ok "Termux without cargo installs the Rust toolchain via pkg" \
+  '[ "$rc" = 0 ] && grep -q "rust rust-std-aarch64-linux-android" "$TMP/tm-pkg.calls"'
+
+printf '#!/usr/bin/env bash\necho "cargo 1.97.1"\nexit 0\n' > "$tm_bin/cargo"
+chmod +x "$tm_bin/cargo"
+: > "$TMP/tm-pkg.calls"
+out="$(HOME="$tm_home" CCC_CLAUDE_DIR="$tm_claude" CCC_HERMES_DIR="$tm_hermes" \
+  TERMUX_VERSION=0.118 PATH="$tm_bin:/usr/local/bin:/usr/bin:/bin" bash "$SETUP" --no-backup 2>&1)"; rc=$?
+ok "Termux with cargo skips pkg install" \
+  '[ "$rc" = 0 ] && [ ! -s "$TMP/tm-pkg.calls" ] && grep -q "Rust toolchain present" <<<"$out"'
+
+rm -f "$tm_bin/cargo"
+: > "$TMP/tm-pkg.calls"
+out="$(HOME="$tm_home" CCC_CLAUDE_DIR="$tm_claude" CCC_HERMES_DIR="$tm_hermes" \
+  TERMUX_VERSION=0.118 PATH="$tm_bin:/usr/local/bin:/usr/bin:/bin" bash "$SETUP" --dry-run 2>&1)"; rc=$?
+ok "Termux dry-run prints but does not run pkg install" \
+  'grep -q "dry-run. pkg install -y rust rust-std-aarch64-linux-android" <<<"$out" && [ ! -s "$TMP/tm-pkg.calls" ]'
 
 echo "----"; echo "PASS=$pass FAIL=$fail"
 [ "$fail" = 0 ]
diff --git a/setup.sh b/setup.sh
index 2c986697..8756e37c 100755
--- a/setup.sh
+++ b/setup.sh
@@ -732,6 +732,30 @@ else
 fi
 note "Existing ccc-telegram-bridge systemd unit checked against the canonical renderer"
 
+# #968: Termux/Android hash-locked installs may need to build packages from
+# source (cryptography 50 has no Android wheel -> maturin -> Rust). A missing
+# toolchain killed the daegyo bridge on 2026-08-06 and the prerequisite lived
+# only in prose. Ensure it here so it is a setup-managed property; when the
+# install cannot run, say so loudly with the exact pkg line.
+IS_TERMUX=0
+[ -n "${TERMUX_VERSION:-}" ] && IS_TERMUX=1
+case "${PREFIX:-}" in */com.termux/*) IS_TERMUX=1 ;; esac
+if [ "$IS_TERMUX" = 1 ]; then
+  if command -v cargo >/dev/null 2>&1; then
+    note "Termux Rust toolchain present ($(cargo --version 2>/dev/null | head -1))"
+  elif [ "$DRY" = 1 ]; then
+    echo "[dry-run] pkg install -y rust rust-std-aarch64-linux-android"
+  elif command -v pkg >/dev/null 2>&1; then
+    if pkg install -y rust rust-std-aarch64-linux-android; then
+      note "installed Termux Rust toolchain (rust + rust-std-aarch64-linux-android)"
+    else
+      note "WARNING: Rust toolchain install failed — hash-locked dependency builds (e.g. cryptography via maturin) will fail. Run: pkg install -y rust rust-std-aarch64-linux-android"
+    fi
+  else
+    note "WARNING: pkg not found — install the Rust toolchain manually: pkg install -y rust rust-std-aarch64-linux-android"
+  fi
+fi
+
 cat <<'EOF'
 
 ==> Done. Follow-up checklist (do these manually):