fix(issue): accept multi-line issue identifiers by keeping first line (CLI-1G1)

src/lib/arg-parsing.ts

@@ -66,6 +66,9 @@ function looksLikeDisplayName(input: string): boolean {
  */
 const ISSUE_SHORT_ID_PATTERN = /^[A-Z][A-Z0-9]*(-[A-Z][A-Z0-9]*)*-[A-Z0-9]+$/;
 
+/** Splits a string into lines on LF or CRLF boundaries. */
+const LINE_SPLIT_PATTERN = /\r?\n/;
+
 /**
  * Check if a string looks like a Sentry issue short ID.
  *
@@ -1084,8 +1087,22 @@ export function parseSlashSeparatedArg(
 }
 
 export function parseIssueArg(arg: string): ParsedIssueArg {
-  // Trim whitespace — agents may pass trailing newlines (CLI-16M)
-  const input = arg.trim();
+  // Take the first non-blank line. A bare `.trim()` only strips leading and
+  // trailing whitespace, so multi-line input (command substitution that
+  // captured extra output, an identifier with an appended note, or several
+  // newline-separated IDs) left an *internal* newline that reached
+  // validateResourceId and threw a cryptic "contains a newline" error
+  // (CLI-1G1, 116+ users). An issue identifier is always a single line, so the
+  // first non-blank line is the intended value. Unlike `sentry api`, which
+  // rejoins wrapped URLs (CLI-FR), identifiers are atomic tokens — joining
+  // lines would produce garbage, so we keep only the first line.
+  // Splitting on `\n` (a control char) never breaks project display names with
+  // spaces (#1116), since those are rejected as control chars anyway.
+  const input =
+    arg
+      .split(LINE_SPLIT_PATTERN)
+      .map((line) => line.trim())
+      .find((line) => line.length > 0) ?? "";
 
   if (!input) {
     throw new ValidationError(

test/lib/arg-parsing.test.ts

@@ -342,6 +342,49 @@ describe("parseIssueArg", () => {
     });
   });
 
+  // Multi-line input (CLI-1G1): agents and shells pass identifiers with
+  // internal newlines (command substitution capturing extra output, an
+  // appended note, or several newline-separated IDs). A bare trim() leaves the
+  // internal newline, which previously threw a cryptic "contains a newline"
+  // ValidationError. We keep the first non-blank line instead.
+  describe("multi-line and whitespace input (CLI-1G1)", () => {
+    const expected = {
+      type: "explicit",
+      org: "sentry",
+      project: "cli",
+      suffix: "G",
+    };
+
+    test("strips a trailing newline (CLI-16M regression)", () => {
+      expect(parseIssueArg("sentry/cli-G\n")).toEqual(expected);
+    });
+
+    test("skips leading blank lines", () => {
+      expect(parseIssueArg("\n\n  sentry/cli-G")).toEqual(expected);
+    });
+
+    test("keeps the first line when a note is appended after a newline", () => {
+      expect(parseIssueArg("sentry/cli-G\nthe auth-token error")).toEqual(
+        expected
+      );
+    });
+
+    test("keeps the first identifier when several are newline-separated", () => {
+      expect(parseIssueArg("sentry/cli-G\nsentry/cli-H")).toEqual(expected);
+    });
+
+    test("handles CRLF line endings", () => {
+      expect(parseIssueArg("sentry/cli-G\r\ntrailing line")).toEqual(expected);
+    });
+
+    test("throws a clear error when input is only blank lines", () => {
+      expect(() => parseIssueArg("\n   \n\t\n")).toThrow(ValidationError);
+      expect(() => parseIssueArg("\n   \n\t\n")).toThrow(
+        /empty after trimming/
+      );
+    });
+  });
+
   // Error cases - verify specific error messages
   describe("error cases", () => {
     test("org/-suffix throws error", () => {