fix(terminal): sanitize skills JSON and fallback on legacy Windows (#43520)

* Terminal: use ASCII borders on legacy Windows consoles

* Skills: sanitize JSON output for control bytes

* Changelog: credit terminal follow-up fixes

* Update CHANGELOG.md

* Update CHANGELOG.md

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

* Skills: strip remaining escape sequences from JSON output

---------

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

src/cli/skills-cli.format.ts

@@ -1,4 +1,5 @@
 import type { SkillStatusEntry, SkillStatusReport } from "../agents/skills-status.js";
+import { stripAnsi } from "../terminal/ansi.js";
 import { getTerminalTableWidth, renderTable } from "../terminal/table.js";
 import { theme } from "../terminal/theme.js";
 import { shortenHomePath } from "../utils.js";
@@ -42,6 +43,33 @@ function normalizeSkillEmoji(emoji?: string): string {
   return (emoji ?? "📦").replaceAll("\uFE0E", "\uFE0F");
 }
 
+const REMAINING_ESC_SEQUENCE_REGEX = new RegExp(
+  String.raw`\u001b(?:[@-Z\\-_]|\[[0-?]*[ -/]*[@-~])`,
+  "g",
+);
+const JSON_CONTROL_CHAR_REGEX = new RegExp(String.raw`[\u0000-\u001f\u007f-\u009f]`, "g");
+
+function sanitizeJsonString(value: string): string {
+  return stripAnsi(value)
+    .replace(REMAINING_ESC_SEQUENCE_REGEX, "")
+    .replace(JSON_CONTROL_CHAR_REGEX, "");
+}
+
+function sanitizeJsonValue(value: unknown): unknown {
+  if (typeof value === "string") {
+    return sanitizeJsonString(value);
+  }
+  if (Array.isArray(value)) {
+    return value.map((item) => sanitizeJsonValue(item));
+  }
+  if (value && typeof value === "object") {
+    return Object.fromEntries(
+      Object.entries(value).map(([key, entryValue]) => [key, sanitizeJsonValue(entryValue)]),
+    );
+  }
+  return value;
+}
+
 function formatSkillName(skill: SkillStatusEntry): string {
   const emoji = normalizeSkillEmoji(skill.emoji);
   return `${emoji} ${theme.command(skill.name)}`;
@@ -71,7 +99,7 @@ export function formatSkillsList(report: SkillStatusReport, opts: SkillsListOpti
   const skills = opts.eligible ? report.skills.filter((s) => s.eligible) : report.skills;
 
   if (opts.json) {
-    const jsonReport = {
+    const jsonReport = sanitizeJsonValue({
       workspaceDir: report.workspaceDir,
       managedSkillsDir: report.managedSkillsDir,
       skills: skills.map((s) => ({
@@ -87,7 +115,7 @@ export function formatSkillsList(report: SkillStatusReport, opts: SkillsListOpti
         homepage: s.homepage,
         missing: s.missing,
       })),
-    };
+    });
     return JSON.stringify(jsonReport, null, 2);
   }
 
@@ -154,7 +182,7 @@ export function formatSkillInfo(
   }
 
   if (opts.json) {
-    return JSON.stringify(skill, null, 2);
+    return JSON.stringify(sanitizeJsonValue(skill), null, 2);
   }
 
   const lines: string[] = [];
@@ -251,7 +279,7 @@ export function formatSkillsCheck(report: SkillStatusReport, opts: SkillsCheckOp
 
   if (opts.json) {
     return JSON.stringify(
-      {
+      sanitizeJsonValue({
         summary: {
           total: report.skills.length,
           eligible: eligible.length,
@@ -267,7 +295,7 @@ export function formatSkillsCheck(report: SkillStatusReport, opts: SkillsCheckOp
           missing: s.missing,
           install: s.install,
         })),
-      },
+      }),
       null,
       2,
     );

src/cli/skills-cli.test.ts

@@ -243,5 +243,46 @@ describe("skills-cli", () => {
       const parsed = JSON.parse(output) as Record<string, unknown>;
       assert(parsed);
     });
+
+    it("sanitizes ANSI and C1 controls in skills list JSON output", () => {
+      const report = createMockReport([
+        createMockSkill({
+          name: "json-skill",
+          emoji: "\u001b[31m📧\u001b[0m\u009f",
+          description: "desc\u0093\u001b[2J\u001b[33m colored\u001b[0m",
+        }),
+      ]);
+
+      const output = formatSkillsList(report, { json: true });
+      const parsed = JSON.parse(output) as {
+        skills: Array<{ emoji: string; description: string }>;
+      };
+
+      expect(parsed.skills[0]?.emoji).toBe("📧");
+      expect(parsed.skills[0]?.description).toBe("desc colored");
+      expect(output).not.toContain("\\u001b");
+    });
+
+    it("sanitizes skills info JSON output", () => {
+      const report = createMockReport([
+        createMockSkill({
+          name: "info-json",
+          emoji: "\u001b[31m🎙\u001b[0m\u009f",
+          description: "hi\u0091",
+          homepage: "https://example.com/\u0092docs",
+        }),
+      ]);
+
+      const output = formatSkillInfo(report, "info-json", { json: true });
+      const parsed = JSON.parse(output) as {
+        emoji: string;
+        description: string;
+        homepage: string;
+      };
+
+      expect(parsed.emoji).toBe("🎙");
+      expect(parsed.description).toBe("hi");
+      expect(parsed.homepage).toBe("https://example.com/docs");
+    });
   });
 });