diff --git a/dep_freshness/_tables.py b/dep_freshness/_tables.py
index 3aa7390..fe0f57c 100644
--- a/dep_freshness/_tables.py
+++ b/dep_freshness/_tables.py
@@ -91,6 +91,8 @@ NPM_ACCEPT: Final = "application/vnd.npm.install-v1+json"
 # --- Cache ------------------------------------------------------------------
 
 CACHE_PATH_ENV: Final = "DEP_FRESHNESS_CACHE"
+# Seconds; overrides every ecosystem TTL (a repo that wants a once-a-day gate).
+TTL_ENV: Final = "DEP_FRESHNESS_TTL_SECONDS"
 DEFAULT_CACHE_DIR: Final = "~/.cache/dep-freshness"
 CACHE_FILE: Final = "registry.json"
 TTL_SECONDS: Final = 6 * 3600
diff --git a/dep_freshness/cache.py b/dep_freshness/cache.py
index 27020ff..be005ba 100644
--- a/dep_freshness/cache.py
+++ b/dep_freshness/cache.py
@@ -21,6 +21,7 @@ from dep_freshness._tables import (
     DEFAULT_CACHE_DIR,
     GITCOMMIT,
     GITTAG,
+    TTL_ENV,
     TTL_GITTAG_SECONDS,
     TTL_SECONDS,
 )
@@ -33,7 +34,14 @@ def cache_dir() -> Path:
 
 
 def ttl_for(ecosystem: str) -> int:
-    """Git refs move rarely and cost a subprocess, so they cache longer."""
+    """Git refs move rarely and cost a subprocess, so they cache longer.
+
+    `DEP_FRESHNESS_TTL_SECONDS` overrides both; garbage is ignored, because a
+    typo in an env var must not break a commit hook.
+    """
+    override = os.environ.get(TTL_ENV, "")
+    if override.isdigit() and int(override) > 0:
+        return int(override)
     return TTL_GITTAG_SECONDS if ecosystem in (GITTAG, GITCOMMIT) else TTL_SECONDS
 
 
diff --git a/dep_freshness/tests/test_resolve.py b/dep_freshness/tests/test_resolve.py
index 556626e..0b19e7e 100644
--- a/dep_freshness/tests/test_resolve.py
+++ b/dep_freshness/tests/test_resolve.py
@@ -12,6 +12,7 @@ from pathlib import Path
 
 import pytest
 
+from dep_freshness._tables import TTL_SECONDS
 from dep_freshness.cache import Cache, Entry, ttl_for
 from dep_freshness.models import Dep
 from dep_freshness.registries import http
@@ -139,3 +140,16 @@ def _offline(*_args):
 
 def _explode(*_args):
     raise RuntimeError("boom")
+
+
+def test_ttl_env_overrides_the_registry_ttl(monkeypatch) -> None:
+    """A repo can stretch the refresh window (once-a-day pre-push gates)."""
+    monkeypatch.setenv("DEP_FRESHNESS_TTL_SECONDS", "86400")
+    assert ttl_for("npm") == 86400
+    assert ttl_for("gittag") == 86400
+
+
+def test_ttl_env_garbage_falls_back_to_the_default(monkeypatch) -> None:
+    """A malformed value must never break a commit hook."""
+    monkeypatch.setenv("DEP_FRESHNESS_TTL_SECONDS", "soon")
+    assert ttl_for("npm") == TTL_SECONDS