fix: sanitize hidden terminal strings in web evidence

docs/research/WEB_EVIDENCE_TERMINAL_STRINGS_2026-10-07.md

@@ -0,0 +1,18 @@
+# Terminal strings in Web evidence
+
+- Status: validated source and regression evidence
+- Created / verified: 2026-10-07
+- Source: origin/main at 3cb2ecfe1bfbb98252651885311d309f83749428
+- Issue: [#700](https://github.com/openpi-dev/openpi/issues/700)
+- Supersedes: none
+
+## Verified facts
+
+Web evidence stripped escape introducers while retaining hidden DCS, PM, APC and SOS payloads. It now uses the canonical shared terminal sanitizer on its bounded candidate. Tests cover ESC/C1 introducers, terminators, unterminated strings and actual tool projections.
+
+## Verification boundary
+
+Eight evidence tests pass. Unicode and tab behavior follows the shared sanitizer. Canonical execution and persisted evidence are unchanged.
+
+Full repository validation results and CI are recorded on the linked PR. Local
+Windows failures are retained separately and are not reported as passing.

tests/web/evidence.test.ts

@@ -17,6 +17,36 @@ function call(name: string, args: Record<string, unknown> = {}) {
   return part;
 }
 
+test("Web evidence strips terminal-owned hidden strings rather than exposing their payloads", () => {
+  for (const start of [
+    "\x1bP",
+    "\x1bX",
+    "\x1b^",
+    "\x1b_",
+    "\u0090",
+    "\u0098",
+    "\u009e",
+    "\u009f",
+  ]) {
+    for (const end of ["\x1b\\", "\u009c"]) {
+      assert.equal(
+        evidenceText(`before${start}hidden${end}after`).text,
+        "beforeafter",
+      );
+    }
+    assert.equal(evidenceText(`before${start}unterminated`).text, "before");
+  }
+  assert.equal(
+    evidenceText("中文\t👩‍💻\x1b[31mvisible\x1b[0m").text,
+    "中文  👩‍💻visible",
+  );
+  const result = projectToolEvidence(call("bash"), {
+    content: "before\x1bPhidden\x1b\\after",
+    isError: false,
+  });
+  assert.equal(result.output, "beforeafter");
+});
+
 test("bounded messages preserve final bash receipts before output truncation", () => {
   const message = projectMessage({
     role: "toolResult",

web/protocol/evidence.ts

@@ -1,4 +1,5 @@
 import type { WebLiveMessage, WebMessagePart } from "./types.ts";
+import { sanitizeTerminalText } from "../../extensions/shared/terminal-text.ts";
 
 export const EVIDENCE_MAX_BYTES = 12 * 1024;
 export const EVIDENCE_MAX_LINES = 300;
@@ -25,10 +26,7 @@ export function projectEvidenceArguments(input: unknown) {
 export function evidenceText(value: string, tail = false) {
   // Bound work before stripping terminal controls, including OSC hyperlinks.
   const candidate = tail ? value.slice(-EVIDENCE_MAX_BYTES * 2) : value.slice(0, EVIDENCE_MAX_BYTES * 2);
-  const clean = candidate
-    .replace(/\x1b\][^\x07\x1b]*(?:\x07|\x1b\\|$)/gu, "")
-    .replace(/(?:\x1b\[|\x9b)[0-?]*[ -/]*[@-~]/gu, "")
-    .replace(/[\x00-\x08\x0b-\x1f\x7f-\x9f\u202a-\u202e\u2066-\u2069]/gu, "");
+  const clean = sanitizeTerminalText(candidate);
   const lines = clean.split("\n");
   const limited = (tail ? lines.slice(-EVIDENCE_MAX_LINES) : lines.slice(0, EVIDENCE_MAX_LINES)).join("\n");
   const bytes = new TextEncoder().encode(limited);