From 1524b06742f736dad6e604d7334007aae87e9cfe Mon Sep 17 00:00:00 2001
From: garrytan <garrytan@gmail.com>
Date: Sun, 1 Nov 2026 02:51:40 +0000
Subject: [PATCH 1/8] fix(secrets): Python/Dart string context comes from the
 diffed text and skips interpolations; pass --diff-base reaches the scoped Red
 Team (GST-738)

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>
---
 bin/gstack-review-dispatch                  |  3 +-
 changelog.d/gst-738-secrets-context.md      |  6 +++
 lib/pregate/checks/secrets.ts               | 46 +++++++++++++++------
 lib/redact-patterns.ts                      | 45 ++++++++++++++++----
 test/pregate-secrets-source-context.test.ts | 18 +++++++-
 test/redact-engine.test.ts                  | 21 ++++++++++
 test/review-pass.test.ts                    | 13 +++++-
 7 files changed, 127 insertions(+), 25 deletions(-)
 create mode 100644 changelog.d/gst-738-secrets-context.md

diff --git a/bin/gstack-review-dispatch b/bin/gstack-review-dispatch
index 827ba0c5b..2174e9979 100755
--- a/bin/gstack-review-dispatch
+++ b/bin/gstack-review-dispatch
@@ -64,6 +64,7 @@ const HELP = `gstack-review-dispatch — verbatim reviewer briefs and loss-free
       runs gstack-review-plan and writes <out>/pass-manifest.json: stage first (audit readers marked first in --extras),
       specialists (with the other --extras readers), red-team, voices (Step 11). Renders first and specialists now; prints
       the plan, MANIFEST: and one READER: line per reader. A plan whose NEXT is not full or scoped prints PASS: none.
+      --diff-base sets every reader's base, a scoped pass's Red Team included (the targeted reader keeps the merge base).
       An existing manifest for the same --pass is reused (resumed). --extras: [{"name","prompt_file","first"?,"model"?}]
   show --manifest <f>                         MANIFEST_JSON: <the manifest on one line>
   stage --manifest <f> --stage <first|specialists|red-team|voices>
@@ -176,7 +177,7 @@ function pass(): number {
   const extras = extrasFile ? JSON.parse(readFile(extrasFile, 'extras')!) as Extra[] : [];
   const m = buildManifest({ pass: id, out, ledger: flag('--ledger') ?? path.join(out, 'review-ledger.jsonl'), base, diffBase, root, checklistRoot: flag('--checklist-root') ?? ROOT,
     dispatches: p.dispatches.filter(d => d.role !== 'fix-check'), next: step, planLines, learnings: readFile(flag('--learnings-file'), 'learnings') ?? null, extras,
-    targetedClasses: p.targeted?.classes, mergeBase, rangeBase });
+    targetedClasses: p.targeted?.classes, mergeBase, rangeBase: flag('--diff-base') ? undefined : rangeBase });
   fs.mkdirSync(m.out, { recursive: true, mode: 0o700 });
   const t = sectionTexts(ROOT);
   renderStage(m, 'first', t, branchDiff);
diff --git a/changelog.d/gst-738-secrets-context.md b/changelog.d/gst-738-secrets-context.md
new file mode 100644
index 000000000..63deeec5c
--- /dev/null
+++ b/changelog.d/gst-738-secrets-context.md
@@ -0,0 +1,6 @@
+**The secrets check reads Python and Dart string context from what git diffed, and a quote inside an interpolation no longer ends a string (GST-738).** env.kv's source-syntax exemption treats a `password:` line as code only when it sits outside every string. Two inputs could make the scanner place a committed string's contents outside a string. One was a working copy that no longer matched what git diffed. The other was a quote inside an f-string or Dart `${…}` expression. A scoped review pass now applies an explicit `--diff-base` to its Red Team as well.
+
+### Fixed
+- **`lib/pregate/checks/secrets.ts`:** a changed Python or Dart file's whole text comes from a full-context `git diff`, never from the working copy.
+- **`lib/redact-patterns.ts`:** a Python f-string's `{…}`, or t-string's, and a non-raw Dart string's `${…}` are skipped whole, nested strings included. A quote inside one doesn't end the outer string. An expression left open runs to the end of the file, so the exemption fails closed.
+- **`bin/gstack-review-dispatch`:** `pass --diff-base` now sets the scoped Red Team's base too.
diff --git a/lib/pregate/checks/secrets.ts b/lib/pregate/checks/secrets.ts
index 934def71c..6adc2bfb9 100644
--- a/lib/pregate/checks/secrets.ts
+++ b/lib/pregate/checks/secrets.ts
@@ -49,6 +49,26 @@ export function parseAddedLineNumbers(diff: string): Map<string, number[]> {
   return files;
 }
 
+/** Each file's whole postimage from a diff with full context: one hunk starting at line 1, its context and added lines; a file with any other shape is left out. */
+export function parsePostimages(diff: string): Map<string, string[]> {
+  const files = new Map<string, string[]>();
+  let file = '';
+  let lines: string[] | null = null;
+  for (const line of diff.split('\n')) {
+    if (line.startsWith('diff --')) { file = ''; lines = null; continue; }
+    if (line.startsWith('@@')) {
+      const first: boolean = lines === null && file !== '' && /^@@ -\d+(?:,\d+)? \+1(?:,\d+)? @@/.test(line);
+      files.delete(file);
+      lines = first ? [] : null;
+      if (lines) files.set(file, lines); else file = '';
+      continue;
+    }
+    if (lines === null) { if (line.startsWith('+++ ')) file = line.startsWith('+++ b/') ? line.slice(6) : ''; continue; }
+    if (line.startsWith('+') || line.startsWith(' ')) lines.push(line.slice(1));
+  }
+  return files;
+}
+
 /** Files whose source-syntax exemption needs the whole file: a line added inside an existing `'''`/`"""` block is a literal (#3630). */
 const LEXICAL_CONTEXT_SOURCE = /\.(?:dart|pyi?)$/i;
 const WHOLE_FILE_MAX_BYTES = 4 * 1024 * 1024;
@@ -58,10 +78,11 @@ const WHOLE_FILE_MAX_BYTES = 4 * 1024 * 1024;
  * untracked files, grouped by file so gstack-redact can use each file's type
  * (#3211). A tracked Dart or Python file is passed whole with `keep`, its
  * added line numbers, so the scanner sees the strings an added line sits in
- * and only findings on those lines count (#3630); an untracked one keeps every
- * line. One too large, unreadable, not a regular file, or whose working copy
- * no longer holds the diff's added lines at their numbers
- * to read whole is scanned under a neutral name, without that exemption. External diff and textconv
+ * and only findings on those lines count (#3630). The whole text is the
+ * postimage git diffed (a full-context diff), never the working copy, which
+ * assume-unchanged can hide from git (GST-738); an untracked file keeps every
+ * line. One too large, or whose full diff does not parse as one hunk holding
+ * its added lines, is scanned under a neutral name, without that exemption. External diff and textconv
  * drivers are off: either can empty or rewrite the diff, and an empty diff
  * reads as clean.
  */
@@ -70,16 +91,15 @@ export function addedLines(ctx: PregateContext): Array<{ file: string; text: str
   const files = parseAddedLines(diff.stdout ?? '');
   const numbers = parseAddedLineNumbers(diff.stdout ?? '');
   const whole = new Map<string, { text: string; keep: number[] }>();
-  for (const [file, keep] of numbers) {
-    if (!LEXICAL_CONTEXT_SOURCE.test(file)) continue;
-    try {
-      const st = fs.lstatSync(path.join(ctx.repoRoot, file));
-      if (!st.isFile() || st.size > WHOLE_FILE_MAX_BYTES) continue;
-      const text = fs.readFileSync(path.join(ctx.repoRoot, file), 'utf8');
-      const lines = text.split('\n');
+  const sources = [...numbers.keys()].filter(file => LEXICAL_CONTEXT_SOURCE.test(file));
+  if (sources.length) {
+    const full = spawnSync('git', ['diff', '--no-color', '--no-ext-diff', '--no-textconv', '--src-prefix=a/', '--dst-prefix=b/', '--unified=100000000', '--diff-filter=ACMR', ctx.mergeBase, '--', ...sources.map(file => `:(literal)${file}`)], { cwd: ctx.repoRoot, encoding: 'utf8', timeout: 60_000, maxBuffer: 256 * 1024 * 1024, env: ctx.env });
+    for (const [file, post] of parsePostimages(full.status === 0 ? full.stdout ?? '' : '')) {
+      const keep = numbers.get(file) ?? [];
       const added = files.get(file) ?? [];
-      if (keep.length === added.length && keep.every((n, k) => lines[n - 1] === added[k])) whole.set(file, { text, keep });
-    } catch { /* unreadable: its added lines are scanned alone */ }
+      const text = post.join('\n');
+      if (text.length <= WHOLE_FILE_MAX_BYTES && keep.length === added.length && keep.every((n, k) => post[n - 1] === added[k])) whole.set(file, { text, keep });
+    }
   }
   for (const t of ctx.touched) {
     if (!t.uncommitted || t.status === 'D') continue;
diff --git a/lib/redact-patterns.ts b/lib/redact-patterns.ts
index 66d837b71..0ba0a7fee 100644
--- a/lib/redact-patterns.ts
+++ b/lib/redact-patterns.ts
@@ -708,6 +708,41 @@ export function clearStringSpanCache(): void {
   stringSpansCache = null;
 }
 
+/**
+ * The string whose quote is at `i`: where its content starts and ends, and the
+ * index after its closing delimiter. An interpolated expression (`{…}` in a
+ * Python f- or t-string, `${…}` in a non-raw Dart string) is skipped whole,
+ * nested strings included, so a quote inside it never ends the outer string
+ * (GST-738); an expression left open runs to the end of the text.
+ */
+function stringAt(text: string, i: number, lang: "py" | "dart"): [number, number, number] {
+  const n = text.length;
+  const c = text[i]!;
+  const close = text.startsWith(c.repeat(3), i) ? c.repeat(3) : c;
+  const multiline = close.length === 3;
+  let k = i;
+  while (k > 0 && /[A-Za-z]/.test(text[k - 1]!)) k -= 1;
+  const prefix = k === 0 || !/[\w$]/.test(text[k - 1]!) ? text.slice(k, i) : "";
+  const raw = lang === "dart" && prefix === "r";
+  const interpolated = lang === "dart" ? !raw : /^(?:[rR]?[fFtT]|[fFtT][rR])$/.test(prefix);
+  let j = i + close.length;
+  while (j < n && !text.startsWith(close, j) && (multiline || text[j] !== "\n")) {
+    if (!raw && text[j] === "\\") { j += 2; continue; }
+    if (!interpolated) { j += 1; continue; }
+    if (lang === "py" && text.startsWith("{{", j)) { j += 2; continue; }
+    if (lang === "py" ? text[j] !== "{" : !text.startsWith("${", j)) { j += 1; continue; }
+    j += lang === "py" ? 1 : 2;
+    for (let depth = 1; j < n && depth > 0; ) {
+      const d = text[j]!;
+      if (d === '"' || d === "'") { j = stringAt(text, j, lang)[2]; continue; }
+      if (d === "{") depth += 1;
+      else if (d === "}") depth -= 1;
+      j += 1;
+    }
+  }
+  return [i + close.length, Math.min(j, n), Math.min(j, n) + close.length];
+}
+
 function stringSpans(text: string, lang: "py" | "dart"): Array<[number, number]> {
   if (stringSpansCache?.text === text && stringSpansCache.lang === lang) return stringSpansCache.spans;
   const spans: Array<[number, number]> = [];
@@ -729,13 +764,9 @@ function stringSpans(text: string, lang: "py" | "dart"): Array<[number, number]>
       continue;
     }
     if (c !== '"' && c !== "'") { i += 1; continue; }
-    const close = text.startsWith(c.repeat(3), i) ? c.repeat(3) : c;
-    const multiline = close.length === 3;
-    const raw = lang === "dart" && text[i - 1] === "r" && !/[\w$]/.test(text[i - 2] ?? "");
-    let j = i + close.length;
-    while (j < n && !text.startsWith(close, j) && (multiline || text[j] !== "\n")) j += !raw && text[j] === "\\" ? 2 : 1;
-    spans.push([i + close.length, Math.min(j, n)]);
-    i = j + close.length;
+    const [from, to, next] = stringAt(text, i, lang);
+    spans.push([from, to]);
+    i = next;
   }
   stringSpansCache = { text, lang, spans };
   return spans;
diff --git a/test/pregate-secrets-source-context.test.ts b/test/pregate-secrets-source-context.test.ts
index a46e1d178..ff7b149d3 100644
--- a/test/pregate-secrets-source-context.test.ts
+++ b/test/pregate-secrets-source-context.test.ts
@@ -99,7 +99,7 @@ describe('pregate secrets: source context and diff integrity', () => {
     } finally { cleanup(fx); }
   });
 
-  test('a Python file whose working copy no longer holds the diff\'s added lines is scanned by its added lines (#3630)', () => {
+  test('a Python file whose working copy no longer holds the diff\'s added lines is scanned as git diffed it (#3630, GST-738)', () => {
     const token = 'Fk2pQ9vXz4wL7mN3rT6yB1cD5eG0hJx';
     const fx: FixtureRepo = makeFixtureRepo({ pregate: BASE_PREGATE, baseFiles: { 'app.py': 'x = 1\n' } });
     try {
@@ -107,7 +107,21 @@ describe('pregate secrets: source context and diff integrity', () => {
       fx.git('update-index', '--assume-unchanged', 'app.py');
       fs.writeFileSync(path.join(fx.work, 'app.py'), 'x = 1\ny = 2\n');
       const check = JSON.parse(runBin(fx, 'gstack-pregate', ['--base', 'main', '--only', 'secrets', '--json']).out).checks.find((c: { id: string }) => c.id === 'secrets');
-      expect({ status: check.status, kv: (check.lines as string[]).some((l) => l.includes('env.kv') && l.includes('app.py, added line 1')) }).toEqual({ status: 'fail', kv: true });
+      expect({ status: check.status, kv: (check.lines as string[]).some((l) => l.includes('env.kv') && l.includes('app.py, line 2')) }).toEqual({ status: 'fail', kv: true });
+    } finally { cleanup(fx); }
+  });
+
+  // Value: protects=the Python/Dart exemption reads the text git diffed, never a working copy that differs from it; fails_when=a committed credential inside a """ block passes because the working copy's other lines were edited under assume-unchanged;
+  //   why_new=GST-738: the added lines matched, so the edited delimiters around them were trusted; seam=git diff; no_claim=a file edited after the scan
+  test('a committed credential in a Python string still fails when the working copy rewrites the lines around it (GST-738)', () => {
+    const token = 'Fk2pQ9vXz4wL7mN3rT6yB1cD5eG0hJx';
+    const fx: FixtureRepo = makeFixtureRepo({ pregate: BASE_PREGATE, baseFiles: { 'app.py': 'x = 1\nCONFIG = """\n"""\n' } });
+    try {
+      commit(fx, { 'app.py': `x = 1\nCONFIG = """\npassword: ${token}\n"""\n` });
+      fx.git('update-index', '--assume-unchanged', 'app.py');
+      fs.writeFileSync(path.join(fx.work, 'app.py'), `x = 1\nCONFIG = 1  #\npassword: ${token}\n#\n`);
+      const check = JSON.parse(runBin(fx, 'gstack-pregate', ['--base', 'main', '--only', 'secrets', '--json']).out).checks.find((c: { id: string }) => c.id === 'secrets');
+      expect({ status: check.status, kv: ((check.lines ?? []) as string[]).some((l) => l.includes('env.kv') && l.includes('app.py')) }).toEqual({ status: 'fail', kv: true });
     } finally { cleanup(fx); }
   });
 
diff --git a/test/redact-engine.test.ts b/test/redact-engine.test.ts
index b25ef1025..9a610b416 100644
--- a/test/redact-engine.test.ts
+++ b/test/redact-engine.test.ts
@@ -347,6 +347,27 @@ describe("MEDIUM demoted credential-shaped patterns (TENSION-1)", () => {
       [`    'password: ${vIdent} more',`, "lib/a.dart"], [`    "password: ${vIdent} more",`, "app.py"],
     ] as const) expect({ literal, file, kv: kv(literal, file) }).toEqual({ literal, file, kv: true });
   });
+  // Value: protects=an interpolated expression inside a Python f-string or Dart string is skipped whole, so a quote inside it never ends the outer string; fails_when=a """/''' delimiter in a nested string closes the block early and a password: line inside it reads as code;
+  //   why_new=GST-738 (outside voice); seam=none; no_claim=Python before 3.12, where the nested quote is a syntax error
+  test("env.kv: a quote inside an f-string or Dart interpolation does not end the string (GST-738)", () => {
+    const kv = (text: string, sourcePath: string) => scan(text, { repoVisibility: "private", sourcePath, processEnv: {} }).findings.some((f) => f.id === "env.kv");
+    const v = "Fk2pQ9vXz4wL7mN3rT6yB1cD5eG0hJx";
+    for (const [literal, file] of [
+      [`CONFIG = f'''\n{"'''"}\npassword: ${v}\n'''\n`, "app.py"],
+      [`CONFIG = rf"""\n{x.replace('"""', "")}\npassword: ${v}\n"""\n`, "app.py"],
+      [`CONFIG = f'''\n{f"{'\'\'\''}"}\npassword: ${v}\n'''\n`, "app.py"],
+      [`const s = '''\${"'''"}\npassword: ${v}\n''';\n`, "lib/a.dart"],
+      [`const s = """\${m["k"] ?? '"""'}\npassword: ${v}\n""";\n`, "lib/a.dart"],
+    ] as const) expect({ literal, kv: kv(literal, file) }).toEqual({ literal, kv: true });
+    for (const [code, file] of [
+      ["msg = f'{a}:{b}'\ndef f(\n    session: HttpSession,\n): pass\n", "app.py"],
+      ["msg = f'''{{literal brace'''\ndef f(\n    session: HttpSession,\n): pass\n", "app.py"],
+      ["msg = f'{x:>{width}}'\ndef f(\n    session: HttpSession,\n): pass\n", "app.py"],
+      ["if'a' in s: pass\ndef f(\n    session: HttpSession,\n): pass\n", "app.py"],
+      ["final s = 'hi ${user.name} and $id';\n  login(password: request.password);\n", "lib/a.dart"],
+      ["final s = r'${raw}';\n  login(password: request.password);\n", "lib/a.dart"],
+    ] as const) expect({ code, kv: kv(code, file) }).toEqual({ code, kv: false });
+  });
   test("env.kv's source-syntax check stays linear on a match-dense file (#3630)", () => {
     for (const file of ["app.py", "src/a.ts"]) {
       const text = "def f(\n" + "    session: HttpSession,\n".repeat(12_000) + "): pass\n";
diff --git a/test/review-pass.test.ts b/test/review-pass.test.ts
index e3458effc..b54256c9c 100644
--- a/test/review-pass.test.ts
+++ b/test/review-pass.test.ts
@@ -492,7 +492,7 @@ describe('the Capy skill loader', () => {
 describe('a scoped pass after a blocker fix (GST-619)', () => {
   // Value: protects=the pass command accepts the scoped plan gstack-review-plan writes after a blocking fix, invoked as GEVA-2 ran it: the Red Team reviews the fix range, Step 11's voices still pending keep the whole branch, the fix-check is named outside the manifest for Step 3.5, and a resumed pass names it again; fails_when=pass refuses the scoped plan, stages the Red Team on the merge base, stages pending Step 11 voices on the range, drops the fix-check silently, or puts it in the manifest;
   //   why_new=GEVA-82 on 1.91.379.0 hit BRIEF_RENDER_FAILED on every scoped pass and rendered briefs by hand; seam=none; no_claim=the fix-check's own brief
-  function scoped(flags: string[]) {
+  function scoped(flags: string[], explicitMergeBase = false) {
     const { dir, env } = repo();
     const sh = (c: string) => { const r = spawnSync('bash', ['-c', c], { cwd: dir, env, encoding: 'utf8', timeout: 60_000 }); if (r.status !== 0) throw new Error(r.stderr); return r.stdout.trim(); };
     const mergeBase = sh('git merge-base main HEAD');
@@ -503,7 +503,7 @@ describe('a scoped pass after a blocker fix (GST-619)', () => {
     fs.mkdirSync(path.join(dir, '.state'), { recursive: true });
     fs.writeFileSync(path.join(dir, '.state/qa.md'), 'QA the fix.\n');
     fs.writeFileSync(extras, JSON.stringify([{ name: 'qa', prompt_file: path.join(dir, '.state/qa.md') }]));
-    const args = ['pass', '--base', 'main', '--out', out, '--pass', 'p2', '--extras', extras, '--', '--pass', '1', '--last', 'full', '--pass1-depth', 'standard', '--fixed-blocking', ...flags, '--range-base', rangeBase.slice(0, 7)];
+    const args = ['pass', '--base', 'main', '--out', out, '--pass', 'p2', '--extras', extras, ...(explicitMergeBase ? ['--diff-base', mergeBase] : []), '--', '--pass', '1', '--last', 'full', '--pass1-depth', 'standard', '--fixed-blocking', ...flags, '--range-base', rangeBase.slice(0, 7)];
     const p = bin(dir, env, args);
     expect(p.status, p.stdout + p.stderr).toBe(0);
     expect(p.stdout).toMatch(/^NEXT: scoped /m);
@@ -544,6 +544,15 @@ describe('a scoped pass after a blocker fix (GST-619)', () => {
     expect(s.m.diff_base).toBe(s.rangeBase);
     expect(s.m.readers.map(r => [r.reader, r.diff_base ?? null])).toEqual([['red-team', s.rangeBase], ['adversarial-native', null], ['audit/qa', null]]);
   }, 120_000);
+
+  // Value: protects=an explicit --diff-base reaches every reader, the Red Team included; fails_when=a scoped pass asked to read the whole branch still stages its Red Team on the fix range; why_new=GST-738 (outside voice); seam=none; no_claim=none
+  test('an explicit --diff-base widens the scoped Red Team too (GST-738)', () => {
+    const s = scoped([], true);
+    expect(s.m.diff_base).toBe(s.mergeBase);
+    const m = settle(s, 'specialists') && settle(s, 'red-team');
+    const redTeam = fs.readFileSync(m.readers.find(r => r.reader === 'red-team')!.file!, 'utf8');
+    expect({ diffBase: m.readers.find(r => r.reader === 'red-team')!.diff_base ?? null, reads: redTeam.includes(s.mergeBase) }).toEqual({ diffBase: null, reads: true });
+  }, 120_000);
 });
 
 describe('readers on a shared machine review the checkout the pass ships (GST-482)', () => {

From 5e65b17bdac97e1346f55b8f716acd47fc9b3921 Mon Sep 17 00:00:00 2001
From: garrytan <garrytan@gmail.com>
Date: Sun, 1 Nov 2026 02:57:03 +0000
Subject: [PATCH 2/8] fix(redact): comments inside an interpolation hold no
 delimiter; a Dart block comment is text (GST-738)

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>
---
 changelog.d/gst-738-secrets-context.md |  2 +-
 lib/redact-patterns.ts                 | 33 +++++++++++++++++++-------
 test/redact-engine.test.ts             |  4 ++++
 3 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/changelog.d/gst-738-secrets-context.md b/changelog.d/gst-738-secrets-context.md
index 63deeec5c..469490fb5 100644
--- a/changelog.d/gst-738-secrets-context.md
+++ b/changelog.d/gst-738-secrets-context.md
@@ -2,5 +2,5 @@
 
 ### Fixed
 - **`lib/pregate/checks/secrets.ts`:** a changed Python or Dart file's whole text comes from a full-context `git diff`, never from the working copy.
-- **`lib/redact-patterns.ts`:** a Python f-string's `{…}`, or t-string's, and a non-raw Dart string's `${…}` are skipped whole, nested strings included. A quote inside one doesn't end the outer string. An expression left open runs to the end of the file, so the exemption fails closed.
+- **`lib/redact-patterns.ts`:** a Python f-string's `{…}`, or t-string's, and a non-raw Dart string's `${…}` are skipped whole, nested strings and comments included. A quote inside one doesn't end the outer string. A `password:` line inside a Dart `/* */` comment is now read as text, not code. An expression left open runs to the end of the file, so the exemption fails closed.
 - **`bin/gstack-review-dispatch`:** `pass --diff-base` now sets the scoped Red Team's base too.
diff --git a/lib/redact-patterns.ts b/lib/redact-patterns.ts
index 0ba0a7fee..171ffbe0e 100644
--- a/lib/redact-patterns.ts
+++ b/lib/redact-patterns.ts
@@ -694,7 +694,8 @@ const CODE_NAME_CHAIN = /^[A-Za-z_$][\w$]*(?:\??\.[A-Za-z_$][\w$]*)*(?:<[\w$.,\s
  * text) records every string's content span: a `'''`/`"""` block, or a
  * `'`/`"` string that ends at its line unless a backslash continues it.
  * Comments are skipped (`#` in Python; `//` and nested `/* *\/` in Dart), so a
- * delimiter inside one opens nothing; a backslash escapes the next character, except in a Dart raw
+ * delimiter inside one opens nothing, and a Dart block comment's own span is
+ * recorded too: a `password:` line in it is text, not code (GST-738); a backslash escapes the next character, except in a Dart raw
  * string (`r'''…'''`). The exemption needs the
  * whole file to see a block's opener: pregate passes Dart and Python files
  * whole, and the pre-push hook, which scans added lines alone, passes them
@@ -708,6 +709,22 @@ export function clearStringSpanCache(): void {
   stringSpansCache = null;
 }
 
+/** The index after the comment at `i`: a line comment ends at its newline, a Dart block comment at its matching `*\/` (they nest). */
+function commentEnd(text: string, i: number, lang: "py" | "dart"): number {
+  if (lang === "py" || !text.startsWith("/*", i)) {
+    const eol = text.indexOf("\n", i);
+    return eol < 0 ? text.length : eol;
+  }
+  let depth = 1;
+  let j = i + 2;
+  while (j < text.length && depth > 0) {
+    if (text.startsWith("/*", j)) { depth += 1; j += 2; }
+    else if (text.startsWith("*/", j)) { depth -= 1; j += 2; }
+    else j += 1;
+  }
+  return j;
+}
+
 /**
  * The string whose quote is at `i`: where its content starts and ends, and the
  * index after its closing delimiter. An interpolated expression (`{…}` in a
@@ -734,6 +751,8 @@ function stringAt(text: string, i: number, lang: "py" | "dart"): [number, number
     j += lang === "py" ? 1 : 2;
     for (let depth = 1; j < n && depth > 0; ) {
       const d = text[j]!;
+      const comment = lang === "py" ? d === "#" : text.startsWith("//", j);
+      if (comment || (lang === "dart" && text.startsWith("/*", j))) { j = commentEnd(text, j, lang); continue; }
       if (d === '"' || d === "'") { j = stringAt(text, j, lang)[2]; continue; }
       if (d === "{") depth += 1;
       else if (d === "}") depth -= 1;
@@ -750,17 +769,13 @@ function stringSpans(text: string, lang: "py" | "dart"): Array<[number, number]>
   for (let i = 0; i < n; ) {
     const c = text[i]!;
     if (lang === "py" ? c === "#" : text.startsWith("//", i)) {
-      const eol = text.indexOf("\n", i);
-      i = eol < 0 ? n : eol;
+      i = commentEnd(text, i, lang);
       continue;
     }
     if (lang === "dart" && text.startsWith("/*", i)) {
-      let depth = 1;
-      for (i += 2; i < n && depth > 0; ) {
-        if (text.startsWith("/*", i)) { depth += 1; i += 2; }
-        else if (text.startsWith("*/", i)) { depth -= 1; i += 2; }
-        else i += 1;
-      }
+      const end = commentEnd(text, i, lang);
+      spans.push([i, end]);
+      i = end;
       continue;
     }
     if (c !== '"' && c !== "'") { i += 1; continue; }
diff --git a/test/redact-engine.test.ts b/test/redact-engine.test.ts
index 9a610b416..f4b8d80f1 100644
--- a/test/redact-engine.test.ts
+++ b/test/redact-engine.test.ts
@@ -358,6 +358,10 @@ describe("MEDIUM demoted credential-shaped patterns (TENSION-1)", () => {
       [`CONFIG = f'''\n{f"{'\'\'\''}"}\npassword: ${v}\n'''\n`, "app.py"],
       [`const s = '''\${"'''"}\npassword: ${v}\n''';\n`, "lib/a.dart"],
       [`const s = """\${m["k"] ?? '"""'}\npassword: ${v}\n""";\n`, "lib/a.dart"],
+      // A comment inside an interpolation holds no delimiter, and a Dart block comment is text.
+      [`CONFIG = f"""\n{1 # } """\n}\npassword: ${v}\n"""\n`, "app.py"],
+      [`const s = '''\${x // '''\n}\npassword: ${v}\n''';\n`, "lib/a.dart"],
+      [`void main() {}\n/*\npassword: ${v}\n*/\n`, "lib/a.dart"],
     ] as const) expect({ literal, kv: kv(literal, file) }).toEqual({ literal, kv: true });
     for (const [code, file] of [
       ["msg = f'{a}:{b}'\ndef f(\n    session: HttpSession,\n): pass\n", "app.py"],

From 51c06507875d15130f47bf68969a92fa9c2b5727 Mon Sep 17 00:00:00 2001
From: garrytan <garrytan@gmail.com>
Date: Sun, 1 Nov 2026 03:04:57 +0000
Subject: [PATCH 3/8] fix(redact): a Python format spec is text, and # is a
 comment only in a triple-quoted f-string (GST-738)

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>
---
 lib/redact-patterns.ts     | 49 ++++++++++++++++++++++++++++++--------
 test/redact-engine.test.ts |  5 ++++
 2 files changed, 44 insertions(+), 10 deletions(-)

diff --git a/lib/redact-patterns.ts b/lib/redact-patterns.ts
index 171ffbe0e..a82e2415c 100644
--- a/lib/redact-patterns.ts
+++ b/lib/redact-patterns.ts
@@ -725,6 +725,44 @@ function commentEnd(text: string, i: number, lang: "py" | "dart"): number {
   return j;
 }
 
+/** The index after a Dart `${…}` expression starting at `j`: braces balance, and its strings and comments are skipped whole. */
+function dartExpressionEnd(text: string, j: number): number {
+  for (let depth = 1; j < text.length && depth > 0; ) {
+    const d = text[j]!;
+    if (text.startsWith("//", j) || text.startsWith("/*", j)) { j = commentEnd(text, j, "dart"); continue; }
+    if (d === '"' || d === "'") { j = stringAt(text, j, "dart")[2]; continue; }
+    if (d === "{") depth += 1;
+    else if (d === "}") depth -= 1;
+    j += 1;
+  }
+  return Math.min(j, text.length);
+}
+
+/**
+ * The index after a Python replacement field whose expression starts at `j`.
+ * The expression's strings, and its `#` comments in a triple-quoted string, are skipped whole; a `:` or `!`
+ * outside its brackets starts the conversion and format spec, which is plain
+ * text apart from nested `{…}` fields (`{n:#x}`, `{n:'>10}`).
+ */
+function pythonFieldEnd(text: string, j: number, multiline: boolean): number {
+  const n = text.length;
+  let nest = 0;
+  while (j < n) {
+    const d = text[j]!;
+    if (d === "#" && multiline) { j = commentEnd(text, j, "py"); continue; }
+    if (d === '"' || d === "'") { j = stringAt(text, j, "py")[2]; continue; }
+    if (d === "}" && nest === 0) return j + 1;
+    if (nest === 0 && (d === ":" || (d === "!" && text[j + 1] !== "="))) {
+      for (j += 1; j < n && text[j] !== "}"; ) j = text[j] === "{" ? pythonFieldEnd(text, j + 1, multiline) : j + 1;
+      return Math.min(j + 1, n);
+    }
+    if ("([{".includes(d)) nest += 1;
+    else if (")]}".includes(d)) nest = Math.max(0, nest - 1);
+    j += 1;
+  }
+  return n;
+}
+
 /**
  * The string whose quote is at `i`: where its content starts and ends, and the
  * index after its closing delimiter. An interpolated expression (`{…}` in a
@@ -748,16 +786,7 @@ function stringAt(text: string, i: number, lang: "py" | "dart"): [number, number
     if (!interpolated) { j += 1; continue; }
     if (lang === "py" && text.startsWith("{{", j)) { j += 2; continue; }
     if (lang === "py" ? text[j] !== "{" : !text.startsWith("${", j)) { j += 1; continue; }
-    j += lang === "py" ? 1 : 2;
-    for (let depth = 1; j < n && depth > 0; ) {
-      const d = text[j]!;
-      const comment = lang === "py" ? d === "#" : text.startsWith("//", j);
-      if (comment || (lang === "dart" && text.startsWith("/*", j))) { j = commentEnd(text, j, lang); continue; }
-      if (d === '"' || d === "'") { j = stringAt(text, j, lang)[2]; continue; }
-      if (d === "{") depth += 1;
-      else if (d === "}") depth -= 1;
-      j += 1;
-    }
+    j = lang === "py" ? pythonFieldEnd(text, j + 1, multiline) : dartExpressionEnd(text, j + 2);
   }
   return [i + close.length, Math.min(j, n), Math.min(j, n) + close.length];
 }
diff --git a/test/redact-engine.test.ts b/test/redact-engine.test.ts
index f4b8d80f1..7055f6bf0 100644
--- a/test/redact-engine.test.ts
+++ b/test/redact-engine.test.ts
@@ -362,11 +362,16 @@ describe("MEDIUM demoted credential-shaped patterns (TENSION-1)", () => {
       [`CONFIG = f"""\n{1 # } """\n}\npassword: ${v}\n"""\n`, "app.py"],
       [`const s = '''\${x // '''\n}\npassword: ${v}\n''';\n`, "lib/a.dart"],
       [`void main() {}\n/*\npassword: ${v}\n*/\n`, "lib/a.dart"],
+      // A format spec is text: its # or quote opens nothing.
+      [`render({\n    "id": f"{n:#x}",\n}, """\npassword: ${v}\n""")\n`, "app.py"],
+      [`render({\n    "id": f"{n:'>10}",\n}, """\npassword: ${v}\n""")\n`, "app.py"],
+      [`render({\n    "id": f"{n!r:{w}}",\n}, """\npassword: ${v}\n""")\n`, "app.py"],
     ] as const) expect({ literal, kv: kv(literal, file) }).toEqual({ literal, kv: true });
     for (const [code, file] of [
       ["msg = f'{a}:{b}'\ndef f(\n    session: HttpSession,\n): pass\n", "app.py"],
       ["msg = f'''{{literal brace'''\ndef f(\n    session: HttpSession,\n): pass\n", "app.py"],
       ["msg = f'{x:>{width}}'\ndef f(\n    session: HttpSession,\n): pass\n", "app.py"],
+      ["msg = f\"{when:%b %d '%y} {d[':']} {a[1:2]} {a!=b}\"\nrows = {\n    \"password\": session.password,\n}\n", "app.py"],
       ["if'a' in s: pass\ndef f(\n    session: HttpSession,\n): pass\n", "app.py"],
       ["final s = 'hi ${user.name} and $id';\n  login(password: request.password);\n", "lib/a.dart"],
       ["final s = r'${raw}';\n  login(password: request.password);\n", "lib/a.dart"],

From 59de715b8da6741f5a2808505b5d7524d68962e3 Mon Sep 17 00:00:00 2001
From: garrytan <garrytan@gmail.com>
Date: Sun, 1 Nov 2026 03:15:41 +0000
Subject: [PATCH 4/8] fix(secrets): suppressBlankEmpty cannot shift the diffed
 text; f-string \{ opens a field; interpolation depth is capped (GST-738)

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>
---
 lib/pregate/checks/secrets.ts               |  2 +-
 lib/redact-patterns.ts                      | 29 ++++++++++++---------
 test/pregate-secrets-source-context.test.ts | 10 +++++++
 test/redact-engine.test.ts                  |  5 ++++
 4 files changed, 33 insertions(+), 13 deletions(-)

diff --git a/lib/pregate/checks/secrets.ts b/lib/pregate/checks/secrets.ts
index 6adc2bfb9..17572c1f4 100644
--- a/lib/pregate/checks/secrets.ts
+++ b/lib/pregate/checks/secrets.ts
@@ -93,7 +93,7 @@ export function addedLines(ctx: PregateContext): Array<{ file: string; text: str
   const whole = new Map<string, { text: string; keep: number[] }>();
   const sources = [...numbers.keys()].filter(file => LEXICAL_CONTEXT_SOURCE.test(file));
   if (sources.length) {
-    const full = spawnSync('git', ['diff', '--no-color', '--no-ext-diff', '--no-textconv', '--src-prefix=a/', '--dst-prefix=b/', '--unified=100000000', '--diff-filter=ACMR', ctx.mergeBase, '--', ...sources.map(file => `:(literal)${file}`)], { cwd: ctx.repoRoot, encoding: 'utf8', timeout: 60_000, maxBuffer: 256 * 1024 * 1024, env: ctx.env });
+    const full = spawnSync('git', ['-c', 'diff.suppressBlankEmpty=false', 'diff', '--no-color', '--no-ext-diff', '--no-textconv', '--src-prefix=a/', '--dst-prefix=b/', '--unified=100000000', '--diff-filter=ACMR', ctx.mergeBase, '--', ...sources.map(file => `:(literal)${file}`)], { cwd: ctx.repoRoot, encoding: 'utf8', timeout: 60_000, maxBuffer: 256 * 1024 * 1024, env: ctx.env });
     for (const [file, post] of parsePostimages(full.status === 0 ? full.stdout ?? '' : '')) {
       const keep = numbers.get(file) ?? [];
       const added = files.get(file) ?? [];
diff --git a/lib/redact-patterns.ts b/lib/redact-patterns.ts
index a82e2415c..7ef840d4b 100644
--- a/lib/redact-patterns.ts
+++ b/lib/redact-patterns.ts
@@ -725,14 +725,17 @@ function commentEnd(text: string, i: number, lang: "py" | "dart"): number {
   return j;
 }
 
+const MAX_INTERPOLATION_DEPTH = 256;
+
 /** The index after a Dart `${…}` expression starting at `j`: braces balance, and its strings and comments are skipped whole. */
-function dartExpressionEnd(text: string, j: number): number {
-  for (let depth = 1; j < text.length && depth > 0; ) {
+function dartExpressionEnd(text: string, j: number, depth: number): number {
+  if (depth > MAX_INTERPOLATION_DEPTH) return text.length;
+  for (let open = 1; j < text.length && open > 0; ) {
     const d = text[j]!;
     if (text.startsWith("//", j) || text.startsWith("/*", j)) { j = commentEnd(text, j, "dart"); continue; }
-    if (d === '"' || d === "'") { j = stringAt(text, j, "dart")[2]; continue; }
-    if (d === "{") depth += 1;
-    else if (d === "}") depth -= 1;
+    if (d === '"' || d === "'") { j = stringAt(text, j, "dart", depth)[2]; continue; }
+    if (d === "{") open += 1;
+    else if (d === "}") open -= 1;
     j += 1;
   }
   return Math.min(j, text.length);
@@ -744,16 +747,17 @@ function dartExpressionEnd(text: string, j: number): number {
  * outside its brackets starts the conversion and format spec, which is plain
  * text apart from nested `{…}` fields (`{n:#x}`, `{n:'>10}`).
  */
-function pythonFieldEnd(text: string, j: number, multiline: boolean): number {
+function pythonFieldEnd(text: string, j: number, multiline: boolean, depth: number): number {
   const n = text.length;
+  if (depth > MAX_INTERPOLATION_DEPTH) return n;
   let nest = 0;
   while (j < n) {
     const d = text[j]!;
     if (d === "#" && multiline) { j = commentEnd(text, j, "py"); continue; }
-    if (d === '"' || d === "'") { j = stringAt(text, j, "py")[2]; continue; }
+    if (d === '"' || d === "'") { j = stringAt(text, j, "py", depth)[2]; continue; }
     if (d === "}" && nest === 0) return j + 1;
     if (nest === 0 && (d === ":" || (d === "!" && text[j + 1] !== "="))) {
-      for (j += 1; j < n && text[j] !== "}"; ) j = text[j] === "{" ? pythonFieldEnd(text, j + 1, multiline) : j + 1;
+      for (j += 1; j < n && text[j] !== "}"; ) j = text[j] === "{" ? pythonFieldEnd(text, j + 1, multiline, depth + 1) : j + 1;
       return Math.min(j + 1, n);
     }
     if ("([{".includes(d)) nest += 1;
@@ -768,9 +772,10 @@ function pythonFieldEnd(text: string, j: number, multiline: boolean): number {
  * index after its closing delimiter. An interpolated expression (`{…}` in a
  * Python f- or t-string, `${…}` in a non-raw Dart string) is skipped whole,
  * nested strings included, so a quote inside it never ends the outer string
- * (GST-738); an expression left open runs to the end of the text.
+ * (GST-738); an expression left open, or nested past MAX_INTERPOLATION_DEPTH,
+ * runs to the end of the text. In a Python f-string `\{` still opens a field.
  */
-function stringAt(text: string, i: number, lang: "py" | "dart"): [number, number, number] {
+function stringAt(text: string, i: number, lang: "py" | "dart", depth = 0): [number, number, number] {
   const n = text.length;
   const c = text[i]!;
   const close = text.startsWith(c.repeat(3), i) ? c.repeat(3) : c;
@@ -782,11 +787,11 @@ function stringAt(text: string, i: number, lang: "py" | "dart"): [number, number
   const interpolated = lang === "dart" ? !raw : /^(?:[rR]?[fFtT]|[fFtT][rR])$/.test(prefix);
   let j = i + close.length;
   while (j < n && !text.startsWith(close, j) && (multiline || text[j] !== "\n")) {
-    if (!raw && text[j] === "\\") { j += 2; continue; }
+    if (!raw && text[j] === "\\") { j += lang === "py" && interpolated && text[j + 1] === "{" ? 1 : 2; continue; }
     if (!interpolated) { j += 1; continue; }
     if (lang === "py" && text.startsWith("{{", j)) { j += 2; continue; }
     if (lang === "py" ? text[j] !== "{" : !text.startsWith("${", j)) { j += 1; continue; }
-    j = lang === "py" ? pythonFieldEnd(text, j + 1, multiline) : dartExpressionEnd(text, j + 2);
+    j = lang === "py" ? pythonFieldEnd(text, j + 1, multiline, depth + 1) : dartExpressionEnd(text, j + 2, depth + 1);
   }
   return [i + close.length, Math.min(j, n), Math.min(j, n) + close.length];
 }
diff --git a/test/pregate-secrets-source-context.test.ts b/test/pregate-secrets-source-context.test.ts
index ff7b149d3..27777514c 100644
--- a/test/pregate-secrets-source-context.test.ts
+++ b/test/pregate-secrets-source-context.test.ts
@@ -125,6 +125,16 @@ describe('pregate secrets: source context and diff integrity', () => {
     } finally { cleanup(fx); }
   });
 
+  test('diff.suppressBlankEmpty does not shift the diffed Python text (GST-738)', () => {
+    const fx: FixtureRepo = makeFixtureRepo({ pregate: BASE_PREGATE, baseFiles: { 'app.py': 'x = 1\n\ny = 2\n' } });
+    try {
+      commit(fx, { 'app.py': 'x = 1\n\ny = 2\nrows = {\n    "password": session.password,\n}\n' });
+      fx.git('config', 'diff.suppressBlankEmpty', 'true');
+      const check = JSON.parse(runBin(fx, 'gstack-pregate', ['--base', 'main', '--only', 'secrets', '--json']).out).checks.find((c: { id: string }) => c.id === 'secrets');
+      expect(check.status).toBe('pass');
+    } finally { cleanup(fx); }
+  });
+
   test('a one-line change to a Python file counts one added line (#3630)', () => {
     const fx: FixtureRepo = makeFixtureRepo({ pregate: BASE_PREGATE, baseFiles: { 'app.py': 'x = 1\n'.repeat(50) } });
     try {
diff --git a/test/redact-engine.test.ts b/test/redact-engine.test.ts
index 7055f6bf0..74c1617f1 100644
--- a/test/redact-engine.test.ts
+++ b/test/redact-engine.test.ts
@@ -366,6 +366,11 @@ describe("MEDIUM demoted credential-shaped patterns (TENSION-1)", () => {
       [`render({\n    "id": f"{n:#x}",\n}, """\npassword: ${v}\n""")\n`, "app.py"],
       [`render({\n    "id": f"{n:'>10}",\n}, """\npassword: ${v}\n""")\n`, "app.py"],
       [`render({\n    "id": f"{n!r:{w}}",\n}, """\npassword: ${v}\n""")\n`, "app.py"],
+      // In an f-string a backslash does not escape the brace after it.
+      [`CONFIG = f"""\\{"""\npassword: ${v}\n"""}"""\n`, "app.py"],
+      // Nesting past the depth cap runs to the end of the text instead of overflowing the stack.
+      ["const s = '" + "${'".repeat(20000) + `\npassword: ${v}\n`, "lib/a.dart"],
+      ["x = f'" + "{a:".repeat(100000) + `\npassword: ${v}\n`, "app.py"],
     ] as const) expect({ literal, kv: kv(literal, file) }).toEqual({ literal, kv: true });
     for (const [code, file] of [
       ["msg = f'{a}:{b}'\ndef f(\n    session: HttpSession,\n): pass\n", "app.py"],

From f96ff5deed824f6081049e6a8a23146d16cfa066 Mon Sep 17 00:00:00 2001
From: garrytan <garrytan@gmail.com>
Date: Sun, 1 Nov 2026 03:24:23 +0000
Subject: [PATCH 5/8] fix(redact): interpolation code is not string text; # is
 a comment in every f-string field (GST-738)

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>
---
 lib/redact-patterns.ts     | 70 ++++++++++++++++++++++++--------------
 test/redact-engine.test.ts |  5 +++
 2 files changed, 50 insertions(+), 25 deletions(-)

diff --git a/lib/redact-patterns.ts b/lib/redact-patterns.ts
index 7ef840d4b..1d7ef39b9 100644
--- a/lib/redact-patterns.ts
+++ b/lib/redact-patterns.ts
@@ -727,13 +727,19 @@ function commentEnd(text: string, i: number, lang: "py" | "dart"): number {
 
 const MAX_INTERPOLATION_DEPTH = 256;
 
-/** The index after a Dart `${…}` expression starting at `j`: braces balance, and its strings and comments are skipped whole. */
-function dartExpressionEnd(text: string, j: number, depth: number): number {
+type Spans = Array<[number, number]>;
+
+/**
+ * The index after a Dart `${…}` expression starting at `j`. Its code is not
+ * text; its strings and block comments add their own spans.
+ */
+function dartExpressionEnd(text: string, j: number, depth: number, spans: Spans): number {
   if (depth > MAX_INTERPOLATION_DEPTH) return text.length;
   for (let open = 1; j < text.length && open > 0; ) {
     const d = text[j]!;
-    if (text.startsWith("//", j) || text.startsWith("/*", j)) { j = commentEnd(text, j, "dart"); continue; }
-    if (d === '"' || d === "'") { j = stringAt(text, j, "dart", depth)[2]; continue; }
+    if (text.startsWith("//", j)) { j = commentEnd(text, j, "dart"); continue; }
+    if (text.startsWith("/*", j)) { const end = commentEnd(text, j, "dart"); spans.push([j, end]); j = end; continue; }
+    if (d === '"' || d === "'") { j = stringAt(text, j, "dart", depth, spans); continue; }
     if (d === "{") open += 1;
     else if (d === "}") open -= 1;
     j += 1;
@@ -743,21 +749,28 @@ function dartExpressionEnd(text: string, j: number, depth: number): number {
 
 /**
  * The index after a Python replacement field whose expression starts at `j`.
- * The expression's strings, and its `#` comments in a triple-quoted string, are skipped whole; a `:` or `!`
- * outside its brackets starts the conversion and format spec, which is plain
- * text apart from nested `{…}` fields (`{n:#x}`, `{n:'>10}`).
+ * The expression is code: its `#` comments are skipped and its strings add
+ * their own spans. A `:` or `!` outside its brackets starts the conversion and
+ * format spec, which is text apart from nested `{…}` fields (`{n:#x}`, `{n:'>10}`).
  */
-function pythonFieldEnd(text: string, j: number, multiline: boolean, depth: number): number {
+function pythonFieldEnd(text: string, j: number, depth: number, spans: Spans): number {
   const n = text.length;
   if (depth > MAX_INTERPOLATION_DEPTH) return n;
   let nest = 0;
   while (j < n) {
     const d = text[j]!;
-    if (d === "#" && multiline) { j = commentEnd(text, j, "py"); continue; }
-    if (d === '"' || d === "'") { j = stringAt(text, j, "py", depth)[2]; continue; }
+    if (d === "#") { j = commentEnd(text, j, "py"); continue; }
+    if (d === '"' || d === "'") { j = stringAt(text, j, "py", depth, spans); continue; }
     if (d === "}" && nest === 0) return j + 1;
     if (nest === 0 && (d === ":" || (d === "!" && text[j + 1] !== "="))) {
-      for (j += 1; j < n && text[j] !== "}"; ) j = text[j] === "{" ? pythonFieldEnd(text, j + 1, multiline, depth + 1) : j + 1;
+      let from = j + 1;
+      for (j += 1; j < n && text[j] !== "}"; ) {
+        if (text[j] !== "{") { j += 1; continue; }
+        if (from < j) spans.push([from, j]);
+        j = pythonFieldEnd(text, j + 1, depth + 1, spans);
+        from = j;
+      }
+      if (from < Math.min(j, n)) spans.push([from, Math.min(j, n)]);
       return Math.min(j + 1, n);
     }
     if ("([{".includes(d)) nest += 1;
@@ -768,14 +781,15 @@ function pythonFieldEnd(text: string, j: number, multiline: boolean, depth: numb
 }
 
 /**
- * The string whose quote is at `i`: where its content starts and ends, and the
- * index after its closing delimiter. An interpolated expression (`{…}` in a
- * Python f- or t-string, `${…}` in a non-raw Dart string) is skipped whole,
- * nested strings included, so a quote inside it never ends the outer string
- * (GST-738); an expression left open, or nested past MAX_INTERPOLATION_DEPTH,
- * runs to the end of the text. In a Python f-string `\{` still opens a field.
+ * Adds the text spans of the string whose quote is at `i` and returns the index
+ * after its closing delimiter. An interpolated expression (`{…}` in a Python
+ * f- or t-string, `${…}` in a non-raw Dart string) is code: it is skipped
+ * whole, with its nested strings as their own spans, so a quote inside it never
+ * ends the outer string (GST-738). An expression left open, or nested past
+ * MAX_INTERPOLATION_DEPTH, is text to the end of the file. In a Python f-string
+ * `\{` still opens a field.
  */
-function stringAt(text: string, i: number, lang: "py" | "dart", depth = 0): [number, number, number] {
+function stringAt(text: string, i: number, lang: "py" | "dart", depth: number, spans: Spans): number {
   const n = text.length;
   const c = text[i]!;
   const close = text.startsWith(c.repeat(3), i) ? c.repeat(3) : c;
@@ -786,19 +800,27 @@ function stringAt(text: string, i: number, lang: "py" | "dart", depth = 0): [num
   const raw = lang === "dart" && prefix === "r";
   const interpolated = lang === "dart" ? !raw : /^(?:[rR]?[fFtT]|[fFtT][rR])$/.test(prefix);
   let j = i + close.length;
+  let from = j;
   while (j < n && !text.startsWith(close, j) && (multiline || text[j] !== "\n")) {
     if (!raw && text[j] === "\\") { j += lang === "py" && interpolated && text[j + 1] === "{" ? 1 : 2; continue; }
     if (!interpolated) { j += 1; continue; }
     if (lang === "py" && text.startsWith("{{", j)) { j += 2; continue; }
     if (lang === "py" ? text[j] !== "{" : !text.startsWith("${", j)) { j += 1; continue; }
-    j = lang === "py" ? pythonFieldEnd(text, j + 1, multiline, depth + 1) : dartExpressionEnd(text, j + 2, depth + 1);
+    if (from < j) spans.push([from, j]);
+    const field = j;
+    const mark = spans.length;
+    j = lang === "py" ? pythonFieldEnd(text, j + 1, depth + 1, spans) : dartExpressionEnd(text, j + 2, depth + 1, spans);
+    if (j >= n) { spans.length = mark; from = field; break; }
+    from = j;
   }
-  return [i + close.length, Math.min(j, n), Math.min(j, n) + close.length];
+  const end = Math.min(j, n);
+  if (from < end) spans.push([from, end]);
+  return end + close.length;
 }
 
-function stringSpans(text: string, lang: "py" | "dart"): Array<[number, number]> {
+function stringSpans(text: string, lang: "py" | "dart"): Spans {
   if (stringSpansCache?.text === text && stringSpansCache.lang === lang) return stringSpansCache.spans;
-  const spans: Array<[number, number]> = [];
+  const spans: Spans = [];
   const n = text.length;
   for (let i = 0; i < n; ) {
     const c = text[i]!;
@@ -813,9 +835,7 @@ function stringSpans(text: string, lang: "py" | "dart"): Array<[number, number]>
       continue;
     }
     if (c !== '"' && c !== "'") { i += 1; continue; }
-    const [from, to, next] = stringAt(text, i, lang);
-    spans.push([from, to]);
-    i = next;
+    i = stringAt(text, i, lang, 0, spans);
   }
   stringSpansCache = { text, lang, spans };
   return spans;
diff --git a/test/redact-engine.test.ts b/test/redact-engine.test.ts
index 74c1617f1..0bdef1556 100644
--- a/test/redact-engine.test.ts
+++ b/test/redact-engine.test.ts
@@ -366,6 +366,8 @@ describe("MEDIUM demoted credential-shaped patterns (TENSION-1)", () => {
       [`render({\n    "id": f"{n:#x}",\n}, """\npassword: ${v}\n""")\n`, "app.py"],
       [`render({\n    "id": f"{n:'>10}",\n}, """\npassword: ${v}\n""")\n`, "app.py"],
       [`render({\n    "id": f"{n!r:{w}}",\n}, """\npassword: ${v}\n""")\n`, "app.py"],
+      // A # comment in a single-quoted f-string's multi-line field holds no delimiter either.
+      [`msg = f"{\n  1 # }" """\n}"\nCONFIG = """\npassword: ${v}\n"""\n`, "app.py"],
       // In an f-string a backslash does not escape the brace after it.
       [`CONFIG = f"""\\{"""\npassword: ${v}\n"""}"""\n`, "app.py"],
       // Nesting past the depth cap runs to the end of the text instead of overflowing the stack.
@@ -377,6 +379,9 @@ describe("MEDIUM demoted credential-shaped patterns (TENSION-1)", () => {
       ["msg = f'''{{literal brace'''\ndef f(\n    session: HttpSession,\n): pass\n", "app.py"],
       ["msg = f'{x:>{width}}'\ndef f(\n    session: HttpSession,\n): pass\n", "app.py"],
       ["msg = f\"{when:%b %d '%y} {d[':']} {a[1:2]} {a!=b}\"\nrows = {\n    \"password\": session.password,\n}\n", "app.py"],
+      // Code inside a multi-line interpolation is code, not string text.
+      ["msg = f\"{\n {\n  'password': request.password,\n }\n}\"\n", "app.py"],
+      ["final s = \"${login(\n  password: request.password,\n)}\";\n", "lib/a.dart"],
       ["if'a' in s: pass\ndef f(\n    session: HttpSession,\n): pass\n", "app.py"],
       ["final s = 'hi ${user.name} and $id';\n  login(password: request.password);\n", "lib/a.dart"],
       ["final s = r'${raw}';\n  login(password: request.password);\n", "lib/a.dart"],

From 4d6784baaf35834d1b9b8ad90f99aae7112c26bc Mon Sep 17 00:00:00 2001
From: garrytan <garrytan@gmail.com>
Date: Sun, 1 Nov 2026 03:32:37 +0000
Subject: [PATCH 6/8] docs(changelog): GST-738 fragment covers the review fixes

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>
---
 changelog.d/gst-738-secrets-context.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/changelog.d/gst-738-secrets-context.md b/changelog.d/gst-738-secrets-context.md
index 469490fb5..7085473c3 100644
--- a/changelog.d/gst-738-secrets-context.md
+++ b/changelog.d/gst-738-secrets-context.md
@@ -1,6 +1,6 @@
 **The secrets check reads Python and Dart string context from what git diffed, and a quote inside an interpolation no longer ends a string (GST-738).** env.kv's source-syntax exemption treats a `password:` line as code only when it sits outside every string. Two inputs could make the scanner place a committed string's contents outside a string. One was a working copy that no longer matched what git diffed. The other was a quote inside an f-string or Dart `${…}` expression. A scoped review pass now applies an explicit `--diff-base` to its Red Team as well.
 
 ### Fixed
-- **`lib/pregate/checks/secrets.ts`:** a changed Python or Dart file's whole text comes from a full-context `git diff`, never from the working copy.
-- **`lib/redact-patterns.ts`:** a Python f-string's `{…}`, or t-string's, and a non-raw Dart string's `${…}` are skipped whole, nested strings and comments included. A quote inside one doesn't end the outer string. A `password:` line inside a Dart `/* */` comment is now read as text, not code. An expression left open runs to the end of the file, so the exemption fails closed.
+- **`lib/pregate/checks/secrets.ts`:** a changed Python or Dart file's whole text comes from a full-context `git diff`, never from the working copy. A `diff.suppressBlankEmpty` setting can't shift its lines.
+- **`lib/redact-patterns.ts`:** a Python f-string's `{…}`, or t-string's, and a non-raw Dart string's `${…}` are read as code. Their nested strings count as strings, and a quote or comment inside them doesn't end the outer string. A Python format spec, such as `{n:#x}`, is text, and `\{` still opens a field. A `password:` line inside a Dart `/* */` comment is now read as text, not code. An expression left open, or nested more than 256 deep, runs to the end of the file, so the exemption fails closed.
 - **`bin/gstack-review-dispatch`:** `pass --diff-base` now sets the scoped Red Team's base too.

From a4cbca25fbca8ddec2a7ed94291b8f62c3b4e762 Mon Sep 17 00:00:00 2001
From: garrytan <garrytan@gmail.com>
Date: Sun, 1 Nov 2026 03:34:14 +0000
Subject: [PATCH 7/8] docs: pregate and review-policy describe the GST-738
 secrets context and --diff-base

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>
---
 docs/pregate.md       | 11 ++++++++---
 docs/review-policy.md |  3 ++-
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/docs/pregate.md b/docs/pregate.md
index 1cc821b6d..3bd12c0ad 100644
--- a/docs/pregate.md
+++ b/docs/pregate.md
@@ -182,7 +182,9 @@ Two stages with separate clocks, both printed:
   changed Python (`.py`, `.pyi`) or Dart file is scanned whole and only
   findings on its added lines count, so a line added inside an existing
   `"""` or `'''` string is still read as a literal; its rows give the file's
-  line number (`app.py, line 10`).
+  line number (`app.py, line 10`). The whole text is the version git diffed
+  (a full-context `git diff`), never the working copy; a file whose full diff
+  does not parse is scanned on its added lines alone, without that context.
 - `strays`: a new file at the repository root, a new top-level directory, or a
   scratch name (`zz-*`, `tmp*`, `scratch*`) anywhere.
 - `literals`: for every changed exported constant or named timeout/retry
@@ -816,8 +818,11 @@ those, each with its scope and its reason:
   (`session: HttpSession,`) and a dict entry or Dart named argument that reads
   a name (`"password": request.password`) are code, not credentials, as they
   are in TypeScript (#3630). Python's keyword form (`password=request.password`)
-  still reports. The same line inside a `"""` docstring is text and still
-  reports; allowlist it by its value. The pre-push hook sees only added lines,
+  still reports. The same line inside a `"""` docstring, any other string or
+  a Dart `/* */` comment is text and still reports; allowlist it by its value.
+  Code inside a Python f-string or t-string `{…}` field, or a non-raw Dart
+  string's `${…}`, is read as code, and its nested strings and quotes do not
+  end the outer string (GST-738). The pre-push hook sees only added lines,
   so it scans Python and Dart lines without this exemption and may still warn
   (MEDIUM, non-blocking) on them.
 
diff --git a/docs/review-policy.md b/docs/review-policy.md
index 283671003..4086c2dd0 100644
--- a/docs/review-policy.md
+++ b/docs/review-policy.md
@@ -505,7 +505,8 @@ ones, and the arm lost blockers. `bin/gstack-review-dispatch` closes both ends:
 6. `pass --base <b> --out <dir> --pass <id> -- <plan flags>` runs one pass from a
    staged manifest (`<dir>/pass-manifest.json`): audit readers marked first, then
    the specialists with QA and the other audits, then the Red Team, then Step 11's
-   voices. Each reviewer keeps its plan entry and is rendered by the same code as
+   voices. `--diff-base` sets every reader's base, a scoped pass's Red Team
+   included; the targeted reader keeps the merge base. Each reviewer keeps its plan entry and is rendered by the same code as
    `render`, once its inputs exist; the Red Team's findings file is the specialists'
    `merged.jsonl` lines byte for byte. A brief leaves the bin in indexed chunks of at
    most 65,536 characters (`chunk`), so no tool output line carries a whole brief and a

From 1ed7877f595dc449fd9d10fc9b82cab242129e30 Mon Sep 17 00:00:00 2001
From: garrytan <garrytan@gmail.com>
Date: Sun, 1 Nov 2026 14:57:44 +0000
Subject: [PATCH 8/8] docs(pregate): untracked and oversized Python/Dart files
 in the secrets stage (GST-738 re-audit)

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>
---
 docs/pregate.md | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/docs/pregate.md b/docs/pregate.md
index 5080c7a9d..78e6c7365 100644
--- a/docs/pregate.md
+++ b/docs/pregate.md
@@ -182,9 +182,10 @@ Two stages with separate clocks, both printed:
   changed Python (`.py`, `.pyi`) or Dart file is scanned whole and only
   findings on its added lines count, so a line added inside an existing
   `"""` or `'''` string is still read as a literal; its rows give the file's
-  line number (`app.py, line 10`). The whole text is the version git diffed
-  (a full-context `git diff`), never the working copy; a file whose full diff
-  does not parse is scanned on its added lines alone, without that context.
+  line number (`app.py, line 10`). A tracked file's whole text is the version
+  git diffed (a full-context `git diff`), never the working copy; an untracked
+  file is read whole from disk. A file over the size limit, or whose full diff
+  does not parse, is scanned on its added lines alone, without that context.
 - `strays`: a new file at the repository root, a new top-level directory, or a
   scratch name (`zz-*`, `tmp*`, `scratch*`) anywhere.
 - `literals`: for every changed exported constant or named timeout/retry