fix(polling): move spinner from stderr to stdout to prevent consola collision

Move the spinner animation in startSpinner/withProgress/poll from
process.stderr to process.stdout. Consola is configured to write
exclusively to stderr, so when log.info() fires inside a withProgress
callback (e.g. "Applied delta patch" during upgrade), it appends
directly after the spinner text on the same stderr line, producing
garbled output like:

  ⠹ Downloading 0.20.0-dev...ℹ Applied delta patch (74.9 KB downloaded)

With the spinner on stdout and consola on stderr, the two streams no
longer collide.

Also adds isPlainOutput() suppression so the spinner is hidden when
stdout is piped or in plain-output mode, preventing ANSI escape codes
from contaminating pipe consumers.

Author: BYK

src/lib/polling.ts

@@ -6,6 +6,7 @@
  */
 
 import { TimeoutError } from "./errors.js";
+import { isPlainOutput } from "./formatters/plain-detect.js";
 import {
   formatProgressLine,
   truncateProgressMessage,
@@ -82,7 +83,8 @@ export async function poll<T>(options: PollOptions<T>): Promise<T> {
   } = options;
 
   const startTime = Date.now();
-  const spinner = json ? null : startSpinner(initialMessage);
+  const suppress = json || isPlainOutput();
+  const spinner = suppress ? null : startSpinner(initialMessage);
 
   try {
     while (Date.now() - startTime < timeoutMs) {
@@ -105,17 +107,21 @@ export async function poll<T>(options: PollOptions<T>): Promise<T> {
     throw new TimeoutError(timeoutMessage, timeoutHint);
   } finally {
     spinner?.stop();
-    if (!json) {
-      process.stderr.write("\n");
+    if (!suppress) {
+      process.stdout.write("\n");
     }
   }
 }
 
 /**
- * Start an animated spinner that writes progress to stderr.
+ * Start an animated spinner that writes progress to stdout.
+ *
+ * Uses stdout so the spinner doesn't collide with consola log messages
+ * on stderr. The spinner is erased before command output is written,
+ * and is suppressed entirely in JSON mode and when stdout is not a TTY.
  *
  * Returns a controller with `setMessage` to update the displayed text
- * and `stop` to halt the animation. Writes directly to `process.stderr`.
+ * and `stop` to halt the animation.
  */
 function startSpinner(initialMessage: string): {
   setMessage: (msg: string) => void;
@@ -130,7 +136,7 @@ function startSpinner(initialMessage: string): {
       return;
     }
     const display = truncateProgressMessage(currentMessage);
-    process.stderr.write(`\r\x1b[K${formatProgressLine(display, tick)}`);
+    process.stdout.write(`\r\x1b[K${formatProgressLine(display, tick)}`);
     tick += 1;
     setTimeout(scheduleFrame, ANIMATION_INTERVAL_MS).unref();
   };
@@ -158,15 +164,15 @@ export type WithProgressOptions = {
 };
 
 /**
- * Run an async operation with an animated spinner on stderr.
+ * Run an async operation with an animated spinner on stdout.
  *
  * The spinner uses the same braille frames as the Seer polling spinner,
  * giving a consistent look across all CLI commands. Progress output goes
- * to stderr, so it never contaminates stdout (safe to use alongside JSON output).
+ * to stdout so it doesn't collide with consola log messages on stderr.
  *
- * When `options.json` is true the spinner is suppressed entirely, matching
- * the behaviour of {@link poll}. This avoids noisy ANSI escape sequences on
- * stderr when agents or CI pipelines consume `--json` output.
+ * The spinner is suppressed when:
+ * - `options.json` is true (JSON mode — no ANSI noise for agents/CI)
+ * - stdout is not a TTY / plain output mode is active (piped output)
  *
  * The callback receives a `setMessage` function to update the displayed
  * message as work progresses (e.g. to show page counts during pagination).
@@ -193,10 +199,10 @@ export async function withProgress<T>(
   options: WithProgressOptions,
   fn: (setMessage: (msg: string) => void) => Promise<T>
 ): Promise<T> {
-  if (options.json) {
-    // JSON mode: skip the spinner entirely, pass a no-op setMessage
+  if (options.json || isPlainOutput()) {
+    // JSON mode or non-TTY: skip the spinner entirely, pass a no-op setMessage
     return fn(() => {
-      /* spinner suppressed in JSON mode */
+      /* spinner suppressed */
     });
   }
 
@@ -206,6 +212,6 @@ export async function withProgress<T>(
     return await fn(spinner.setMessage);
   } finally {
     spinner.stop();
-    process.stderr.write("\r\x1b[K");
+    process.stdout.write("\r\x1b[K");
   }
 }

test/commands/issue/utils.test.ts

@@ -1058,16 +1058,20 @@ describe("pollAutofixState", () => {
     expect(fetchCount).toBe(2);
   });
 
-  test("writes progress to stderr when not in JSON mode", async () => {
-    let stderrOutput = "";
+  test("writes progress to stdout when not in JSON mode", async () => {
+    let stdoutOutput = "";
     let fetchCount = 0;
 
-    // Spy on process.stderr.write to capture spinner output
-    const origWrite = process.stderr.write.bind(process.stderr);
-    process.stderr.write = ((chunk: string | Uint8Array) => {
-      stderrOutput += String(chunk);
+    // Force rich output so the spinner isn't suppressed in non-TTY test env
+    const origPlain = process.env.SENTRY_PLAIN_OUTPUT;
+    process.env.SENTRY_PLAIN_OUTPUT = "0";
+
+    // Spy on process.stdout.write to capture spinner output
+    const origWrite = process.stdout.write.bind(process.stdout);
+    process.stdout.write = ((chunk: string | Uint8Array) => {
+      stdoutOutput += String(chunk);
       return true;
-    }) as typeof process.stderr.write;
+    }) as typeof process.stdout.write;
 
     try {
       // Return PROCESSING first to allow animation interval to fire,
@@ -1127,9 +1131,14 @@ describe("pollAutofixState", () => {
         pollIntervalMs: 100, // Allow animation interval (80ms) to fire
       });
 
-      expect(stderrOutput).toContain("Analyzing");
+      expect(stdoutOutput).toContain("Analyzing");
     } finally {
-      process.stderr.write = origWrite;
+      process.stdout.write = origWrite;
+      if (origPlain === undefined) {
+        delete process.env.SENTRY_PLAIN_OUTPUT;
+      } else {
+        process.env.SENTRY_PLAIN_OUTPUT = origPlain;
+      }
     }
   });
 
@@ -1505,16 +1514,20 @@ describe("ensureRootCauseAnalysis", () => {
     expect(triggerCalled).toBe(true); // Should trigger even though state exists
   });
 
-  test("writes progress messages to stderr when not in JSON mode", async () => {
-    let stderrOutput = "";
+  test("writes progress messages to stdout when not in JSON mode", async () => {
+    let stdoutOutput = "";
     let triggerCalled = false;
 
-    // Spy on process.stderr.write to capture logger output
-    const origWrite = process.stderr.write.bind(process.stderr);
-    process.stderr.write = ((chunk: string | Uint8Array) => {
-      stderrOutput += String(chunk);
+    // Force rich output so the spinner isn't suppressed in non-TTY test env
+    const origPlain = process.env.SENTRY_PLAIN_OUTPUT;
+    process.env.SENTRY_PLAIN_OUTPUT = "0";
+
+    // Spy on process.stdout.write to capture spinner output
+    const origWrite = process.stdout.write.bind(process.stdout);
+    process.stdout.write = ((chunk: string | Uint8Array) => {
+      stdoutOutput += String(chunk);
       return true;
-    }) as typeof process.stderr.write;
+    }) as typeof process.stdout.write;
 
     try {
       // @ts-expect-error - partial mock
@@ -1566,11 +1579,15 @@ describe("ensureRootCauseAnalysis", () => {
         json: false, // Not JSON mode, should output progress
       });
 
-      // The logger.info() messages go through consola and the poll spinner
-      // writes directly to stderr — check for the spinner's initial message
-      expect(stderrOutput).toContain("Waiting for analysis");
+      // The poll spinner writes to stdout — check for the spinner's initial message
+      expect(stdoutOutput).toContain("Waiting for analysis");
     } finally {
-      process.stderr.write = origWrite;
+      process.stdout.write = origWrite;
+      if (origPlain === undefined) {
+        delete process.env.SENTRY_PLAIN_OUTPUT;
+      } else {
+        process.env.SENTRY_PLAIN_OUTPUT = origPlain;
+      }
     }
   });
 });