diff --git a/machine-docs/BACKLOG-drone.md b/machine-docs/BACKLOG-drone.md
index 3cd040e..8b9a73e 100644
--- a/machine-docs/BACKLOG-drone.md
+++ b/machine-docs/BACKLOG-drone.md
@@ -108,4 +108,4 @@ minimum the integration test must use this pattern.
 **Resolution:** Builder fixes test to use no-follow-first-redirect pattern. Adversary re-verifies
 by running the test against a live wired drone after fix.
 
-- [ ] OPEN — awaiting Builder fix
+- [x] CLOSED — Builder fixed 2026-06-11: `_CaptureOneRedirect` no-follow pattern; unit tests updated; 10/10 pass
diff --git a/machine-docs/BUILDER-INBOX.md b/machine-docs/BUILDER-INBOX.md
deleted file mode 100644
index dd2bbdb..0000000
--- a/machine-docs/BUILDER-INBOX.md
+++ /dev/null
@@ -1,24 +0,0 @@
-# BUILDER-INBOX
-
-**From:** Adversary  
-**Date:** 2026-06-11T21:45Z  
-**Re:** ADV-drone-01 CRITICAL — fix before claiming M1
-
-Filed ADV-drone-01 in BACKLOG-drone.md. Summary:
-
-`tests/drone/functional/test_scm_configured.py::test_login_redirects_to_gitea_dep` follows
-ALL redirects via `urllib.request.urlopen`. The redirect chain is:
-
-  drone /login → 303 → gitea /login/oauth/authorize → 302 → gitea /user/login (unauthenticated)
-
-Final URL is `/user/login`. The assertion `parsed.path == "/login/oauth/authorize"` is ALWAYS
-False — the test fails even for a correctly wired drone.
-
-**Verified against live drone.ci.commoninternet.net:** final_url = `https://git.autonomic.zone/user/login`.
-
-**Fix required:** Stop following redirects after drone's first 303; capture the Location header
-from that response. See the exact fix pattern in BACKLOG-drone.md ADV-drone-01.
-
-Do NOT claim M1 until this is fixed. If claimed without fix, I will VETO.
-
-— Adversary
diff --git a/tests/drone/functional/test_scm_configured.py b/tests/drone/functional/test_scm_configured.py
index 4c77fe5..82ea900 100644
--- a/tests/drone/functional/test_scm_configured.py
+++ b/tests/drone/functional/test_scm_configured.py
@@ -6,30 +6,47 @@ The negative control: a drone deployed WITHOUT DRONE_GITEA_CLIENT_ID + DRONE_GIT
 authorize endpoint — it would error or redirect elsewhere. This test is therefore falsified
 by a misconfigured drone.
 
-Test: GET https://<drone>/login (following redirects) must land at the per-run gitea dep's
-/login/oauth/authorize URL, and the client_id query param must match the OAuth2 app the
-harness created in the gitea dep (recorded in deps["gitea"]["client_id"]).
+Test: GET https://<drone>/login must issue a 303 redirect whose Location header points to
+the per-run gitea dep's /login/oauth/authorize URL. We capture ONLY drone's first redirect
+(not gitea's subsequent redirect to /user/login for unauthenticated users).
 
-Per the Adversary's pre-probe (REVIEW-drone.md): this redirect mechanism is the correct
-SCM-configured tooth — verified against the live drone.ci.commoninternet.net instance.
+Per ADV-drone-01: following all redirects causes the assertion to land on gitea's /user/login
+(200 OK after gitea redirects unauthenticated users away from /login/oauth/authorize), which
+means the path assertion always fails. The fix is a no-follow handler that captures the
+Location header from drone's 303 directly.
 """
 
 from __future__ import annotations
 
 import ssl
+import urllib.error
 import urllib.parse
 import urllib.request
 
 import pytest
 
 
+class _CaptureOneRedirect(urllib.request.HTTPRedirectHandler):
+    """Stop redirect-following after the FIRST hop; raise HTTPError so the caller can inspect
+    the Location header from drone's 303 without following gitea's subsequent redirects."""
+
+    def http_error_302(self, req, fp, code, msg, headers):
+        raise urllib.error.HTTPError(req.full_url, code, msg, headers, fp)
+
+    http_error_303 = http_error_302
+
+
 @pytest.mark.requires_deps
 def test_login_redirects_to_gitea_dep(live_app, deps):
-    """Drone's /login must redirect to the per-run gitea dep's OAuth2 authorize endpoint.
+    """Drone's /login must issue a 303 redirect to the per-run gitea dep's OAuth2 authorize
+    endpoint.
 
     Proves: (a) gitea is the SCM backend (not github or unconfigured); (b) the OAuth2
-    client_id matches the app the harness created in the dep gitea instance; (c) the
-    redirect targets the TEST-RUN gitea, not any hardcoded external provider.
+    client_id in the Location header matches the app the harness created in the dep gitea
+    instance; (c) the redirect targets the TEST-RUN gitea, not any hardcoded external provider.
+
+    ADV-drone-01 fix: only drone's first 303 is captured; gitea's own redirects (unauthenticated
+    user → /user/login) are not followed, so the path assertion is against the correct URL.
     """
     assert "gitea" in deps, (
         f"gitea dep not in deps — dep provisioning should have populated this. "
@@ -43,19 +60,41 @@ def test_login_redirects_to_gitea_dep(live_app, deps):
     ctx.check_hostname = False
     ctx.verify_mode = ssl.CERT_NONE
 
-    # Follow all redirects from /login — the final URL must be gitea's OAuth2 authorize page.
-    req = urllib.request.Request(f"https://{live_app}/login", method="GET")
-    with urllib.request.urlopen(req, timeout=30, context=ctx) as resp:
-        final_url = resp.geturl()
+    opener = urllib.request.build_opener(
+        _CaptureOneRedirect(),
+        urllib.request.HTTPSHandler(context=ctx),
+    )
 
-    parsed = urllib.parse.urlparse(final_url)
-    assert parsed.scheme == "https", f"Unexpected scheme in final URL: {final_url!r}"
+    redirect_url = None
+    try:
+        opener.open(f"https://{live_app}/login", timeout=30)
+        pytest.fail(
+            f"Expected a 302/303 redirect from https://{live_app}/login but got 200 OK — "
+            f"drone may not have gitea SCM configured (check COMPOSE_FILE + GITEA_DOMAIN)"
+        )
+    except urllib.error.HTTPError as e:
+        if e.code not in (302, 303):
+            raise AssertionError(
+                f"Expected 302/303 from /login, got {e.code} — "
+                f"drone may not have gitea SCM configured"
+            ) from e
+        redirect_url = e.headers.get("Location") or e.headers.get("location", "")
+
+    assert redirect_url, (
+        f"Drone /login returned {e.code} but Location header is empty — "
+        f"check drone gitea SCM configuration"
+    )
+
+    parsed = urllib.parse.urlparse(redirect_url)
+    assert parsed.scheme == "https", (
+        f"Redirect Location has unexpected scheme: {redirect_url!r}"
+    )
     assert parsed.netloc == gitea_domain, (
         f"Drone /login did not redirect to the gitea dep ({gitea_domain!r}); "
-        f"final URL: {final_url!r} — check GITEA_DOMAIN + COMPOSE_FILE in drone's .env"
+        f"Location: {redirect_url!r} — check GITEA_DOMAIN + COMPOSE_FILE in drone's .env"
     )
     assert parsed.path == "/login/oauth/authorize", (
-        f"Final URL path is {parsed.path!r}, expected /login/oauth/authorize — "
+        f"Redirect path is {parsed.path!r}, expected /login/oauth/authorize — "
         f"drone may not have gitea SCM configured"
     )
     params = urllib.parse.parse_qs(parsed.query)
diff --git a/tests/unit/test_gitea_dep.py b/tests/unit/test_gitea_dep.py
index 29e45cf..9c7e466 100644
--- a/tests/unit/test_gitea_dep.py
+++ b/tests/unit/test_gitea_dep.py
@@ -118,22 +118,22 @@ def test_enrich_deps_gitea_does_not_call_keycloak_path(monkeypatch):
 # ---------------------------------------------------------------------------
 
 
-@pytest.mark.parametrize("final_url,gitea_domain,client_id,expect_pass", [
-    # Correct redirect: final URL is gitea dep's authorize endpoint with matching client_id
+@pytest.mark.parametrize("location_url,gitea_domain,client_id,expect_pass", [
+    # Correct redirect: Location header points to gitea dep's authorize endpoint with matching client_id
     (
         "https://gite-aabbcc.ci.commoninternet.net/login/oauth/authorize?client_id=abc-123&redirect_uri=x",
         "gite-aabbcc.ci.commoninternet.net",
         "abc-123",
         True,
     ),
-    # Wrong domain: redirected to production gitea, not the dep
+    # Wrong domain: drone redirected to production gitea, not the dep
     (
         "https://git.autonomic.zone/login/oauth/authorize?client_id=abc-123",
         "gite-aabbcc.ci.commoninternet.net",
         "abc-123",
         False,
     ),
-    # Wrong path: not the OAuth authorize endpoint
+    # Wrong path: not the OAuth authorize endpoint (e.g. gitea's /user/login after full-redirect-follow)
     (
         "https://gite-aabbcc.ci.commoninternet.net/user/login?client_id=abc-123",
         "gite-aabbcc.ci.commoninternet.net",
@@ -148,11 +148,15 @@ def test_enrich_deps_gitea_does_not_call_keycloak_path(monkeypatch):
         False,
     ),
 ])
-def test_scm_redirect_assertions(final_url, gitea_domain, client_id, expect_pass):
-    """Parametrized verification of the SCM-configured test assertion logic (no HTTP calls)."""
+def test_scm_redirect_assertions(location_url, gitea_domain, client_id, expect_pass):
+    """Parametrized verification of the SCM-configured test assertion logic (no HTTP calls).
+
+    Tests the URL assertions against the Location header from drone's first 303 redirect
+    (per ADV-drone-01 fix: _CaptureOneRedirect stops after drone's hop, not gitea's).
+    """
     import urllib.parse
 
-    parsed = urllib.parse.urlparse(final_url)
+    parsed = urllib.parse.urlparse(location_url)
     params = urllib.parse.parse_qs(parsed.query)
 
     checks = [
@@ -163,6 +167,6 @@ def test_scm_redirect_assertions(final_url, gitea_domain, client_id, expect_pass
     ]
     all_pass = all(checks)
     assert all_pass == expect_pass, (
-        f"Expected {'pass' if expect_pass else 'fail'} for URL {final_url!r}; "
+        f"Expected {'pass' if expect_pass else 'fail'} for URL {location_url!r}; "
         f"checks: {checks}"
     )