fix(redact): the env.value allowlist and placeholder rules see the normalized value too

An allowlisted value in NFC did not suppress a match on its NFKC-composed
form, and a value that is a placeholder only after normalization was still
searched for. Fixture nits from the third review cycle: fixed directory
string instead of process.cwd(), the fullwidth assertion guards its own
vacuity, a zero-width-padded value under the floor is pinned, and the
ratchet comment names the one kept export and the PATH case line.

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

lib/redact-engine.ts

@@ -476,10 +476,10 @@ function scanInternal(input: string, opts: ScanOptions, spans?: Map<Finding, Ori
   // Environment values, by exact value: a credential that is already in the
   // process environment needs no shape to be recognized.
   for (const { name, value: raw } of credentialEnvValues(opts.processEnv ?? process.env)) {
-    if (allow.has(raw)) continue;
-    // The text was normalized before matching; the value takes the same form.
+    // The text was normalized before matching; the value takes the same form,
+    // and the allowlist and placeholder rules see both forms.
     const value = normalizeOriginal(raw).normalized;
-    if (value.length < MIN_ENV_VALUE_LENGTH) continue;
+    if (allow.has(raw) || allow.has(value) || value.length < MIN_ENV_VALUE_LENGTH || isPlaceholderSpan(value)) continue;
     let from = 0;
     let normOffset: number;
     while ((normOffset = normalized.indexOf(value, from)) !== -1) {
@@ -538,7 +538,9 @@ const MIN_ENV_VALUE_LENGTH = 8;
  * match ordinary prose. There is no path exemption on purpose: a shape rule
  * exempted base64 secrets that start with `/`, and an existence check let the
  * scanned agent exempt a value by creating a path of that name; a path-valued
- * SSL_KEY that must appear in a text goes through the allowlist. The value is
+ * SSL_KEY that must appear in a text goes through `allowlist` where a caller
+ * passes one (`gstack-redact`, the pre-push hook), else the variable is set
+ * empty for that one command. The value is
  * trimmed, so a key read from a file with a trailing newline still matches its
  * leaked form; it is matched against the normalized text in its own normalized
  * form, so a value NFKC rewrites still finds its leaked bytes.

test/launch-env-echo-ratchet.test.ts

@@ -182,8 +182,9 @@ describe('launch-env echo ratchet', () => {
     expect(installer).toContain('LAUNCH_FILE="${VERDICT%.json}.env"');
     expect(installer).toContain('chmod 0600 "$tmp"');
     for (const name of CAPY_LAUNCH_MARKERS) expect(installer, name).toMatch(new RegExp(`^\\s*echo "export ${name}=`, 'm'));
-    // Both directions: every variable the launch file exports is either a marker the shard sandbox
-    // and the test preload strip, or one of the two they keep on purpose (GSTA-99).
+    // Both directions: every `export NAME=` line the launch file writes is either a marker the shard
+    // sandbox and the test preload strip, or GSTACK_STATE_ROOT, which they keep on purpose (GSTA-99).
+    // The PATH prepend is a separate `case` line this regex ignores; PATH is kept too.
     const exported = [...installer.matchAll(/^\s*echo "export ([A-Z_]+)=/gm)].map(m => m[1]).sort();
     expect(exported).toEqual([...CAPY_LAUNCH_MARKERS, 'GSTACK_STATE_ROOT'].sort());
     expect(installer).toContain('echo "GSTACK_LAUNCH_FILE: $LAUNCH_FILE"');

test/redact-env-value.test.ts

@@ -147,11 +147,12 @@ describe("env-value scan", () => {
   // (1) the name rule also admits *_PASS, *_PAT, *_APIKEY and *_PWD, while the shell's own PWD and
   // OLDPWD stay out by NAME (their fixture values are plain words, so only the name rule keeps them
   // out); (2) there is no path exemption: a path-valued SSL_KEY and a base64 secret starting with
-  // "/" are both scanned, and an existing directory as a value changes nothing (an existence check
+  // "/" are both scanned, and a directory path as a value changes nothing (an existence check
   // let the scanned agent exempt a value by creating a path of that name); (3) gstack's own
   // GSTACK_BRAIN_LOCK_TOKEN (pid-random-epoch, written to the lock owner file) is not a secret, and
   // bin/gstack-brain-lock.sh still exports every name in that set; (4) a value NFKC rewrites
-  // (fullwidth digits) is matched in its normalized form, so its leaked ASCII form is found.
+  // (fullwidth digits) is matched in its normalized form, so its leaked ASCII form is found, and a
+  // value whose normalized form is under eight characters is not searched for.
   // fails_when: PWD is admitted (every mention of the cwd becomes HIGH), a shape or existence rule
   // returns (the slash secret or the directory value is skipped), the non-secret set drifts, or the
   // value is matched raw against the normalized text.
@@ -159,7 +160,7 @@ describe("env-value scan", () => {
     const names = credentialEnvValues({
       DB_PASS: dbValue, GITHUB_PAT: ghValue, STRIPE_APIKEY: lowerCaseValue, MYSQL_PWD: dbPasswdValue,
       PWD: "workspace-dir-name", OLDPWD: "previous-dir-name",
-      SSL_KEY: sslKeyPath, DIR_KEY: process.cwd(), SLASH_KEY: slashSecret,
+      SSL_KEY: sslKeyPath, DIR_KEY: "/usr/local/share/ca-certificates", SLASH_KEY: slashSecret,
       GSTACK_BRAIN_LOCK_TOKEN: lockOwner,
     }).map(e => e.name).sort();
     expect(names).toEqual(["DB_PASS", "DIR_KEY", "GITHUB_PAT", "MYSQL_PWD", "SLASH_KEY", "SSL_KEY", "STRIPE_APIKEY"]);
@@ -167,7 +168,10 @@ describe("env-value scan", () => {
     const lock = fs.readFileSync(path.join(import.meta.dir, "..", "bin", "gstack-brain-lock.sh"), "utf8");
     for (const name of NON_SECRET_ENV_NAMES) expect(lock, name).toContain(`export ${name}`);
     const fullwidth = anthropicValue.replace(/[0-9]/g, c => String.fromCharCode(c.charCodeAt(0) + 0xfee0));
+    expect(fullwidth).not.toBe(anthropicValue);
     expect(scan(`leak: ${anthropicValue} end`, { processEnv: { WIDE_KEY: fullwidth } }).findings.map(f => f.id)).toEqual(["env.value"]);
+    const zeroWidthPadded = "ab\u200bcd\u200bef\u200bg";
+    expect(scan("plain abcdefg here", { processEnv: { ZW_KEY: zeroWidthPadded } }).findings).toEqual([]);
   });
 
   test("the default environment is process.env", () => {