diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8a01124b..19ec5e81 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -273,6 +273,13 @@ All notable changes to vouch are documented here. Format follows
   in config.yaml (#476).
 
 ### Fixed
+- secret masking now catches JSON/quoted-key credentials
+  (`"password": "..."`, `'api_key': '...'`). the key's closing quote sat
+  between the name and the `:` and broke the assignment regex, so the most
+  common structured secret shape — and exactly the file family vouch writes
+  (settings.json, quoted yaml) — slipped through `capture.observe` into the
+  gitignored buffer that rolls into a committed session page and the
+  append-only audit log. the value is masked and the key/quotes kept legible (#549).
 - approve/reject/expire record the audit event *before* moving the
   proposal to decided/. a crash between the two used to leave a durable
   decision with no authoritative history; it now leaves a pending
diff --git a/src/vouch/secrets.py b/src/vouch/secrets.py
index d6a5a832..1aa810d0 100644
--- a/src/vouch/secrets.py
+++ b/src/vouch/secrets.py
@@ -36,10 +36,15 @@
 _BEARER = re.compile(r"(?i)\b(Bearer)\s+[A-Za-z0-9._~+/=-]{10,}")
 
 # key=value / key: value for sensitive-looking names — mask the value, keep the
-# name so the redaction is legible.
+# name so the redaction is legible. the optional quote after the name captures a
+# json/quoted-key shape (`"password": "..."`, `'api_key': '...'`) — the single
+# most common structured form a pasted credential takes, and exactly the file
+# family (settings.json, quoted yaml) this codebase writes. without it the key's
+# closing quote sat between the name and the `:` and broke the match, so those
+# leaked. it is inside the captured separator group so the quote is preserved.
 _ASSIGNMENT = re.compile(
     r"(?i)\b(api[_-]?key|secret|token|password|passwd|pwd|access[_-]?key)\b"
-    r"(\s*[:=]\s*)"
+    r"([\"']?\s*[:=]\s*)"
     r"[\"']?[^\s\"']{6,}[\"']?"
 )
 
diff --git a/tests/test_secrets.py b/tests/test_secrets.py
index f293e108..a51e5e24 100644
--- a/tests/test_secrets.py
+++ b/tests/test_secrets.py
@@ -40,6 +40,35 @@ def test_masks_key_value_assignment_but_keeps_the_key_name() -> None:
     assert "PASSWORD" in out
 
 
+def test_masks_json_and_quoted_key_credentials() -> None:
+    """A quoted key — JSON `"password": "..."` or quoted-YAML/py — is the most
+    common structured shape a pasted credential takes, and exactly what this
+    codebase writes (settings.json). The key's closing quote used to sit
+    between the name and the `:` and break the match, so these leaked."""
+    for text, secret in (
+        ('"password": "hunter2supersecret"', "hunter2supersecret"),
+        ("'api_key': 'swordfishalpha'", "swordfishalpha"),
+        ('"secret":"nowhitespacehere"', "nowhitespacehere"),
+    ):
+        out = mask_secrets(text)
+        assert secret not in out, text
+        assert REDACTION in out
+        assert contains_secret(text) is True
+    # the key name and its quotes stay legible
+    assert '"password":' in mask_secrets('"password": "hunter2supersecret"')
+
+
+def test_quoted_key_masking_no_false_positive() -> None:
+    """The quoted-key change must not mask a sensitive-looking word that has
+    no assignment (no separator, or a too-short value)."""
+    for text in (
+        '"password" is required for login',   # quote but no `:`/`=`
+        "password: hi",                        # value under the 6-char floor
+    ):
+        assert mask_secrets(text) == text
+        assert contains_secret(text) is False
+
+
 def test_masks_private_key_block() -> None:
     begin = f"-----BEGIN RSA {_PK}-----"
     end = f"-----END RSA {_PK}-----"