diff --git a/.agents/rules/development/coding-conventions.md b/.agents/rules/development/coding-conventions.md
index 52ed376ee..1f79c449d 100644
--- a/.agents/rules/development/coding-conventions.md
+++ b/.agents/rules/development/coding-conventions.md
@@ -18,3 +18,8 @@ description: Core coding conventions for the abapify monorepo. TypeScript strict
 - Cross-package imports: `@abapify/<package-name>`
 - Internal file imports: extensionless relative paths — see [bundler-imports](bundler-imports.md) for details
 - `workspace:*` protocol for local workspace deps — see `$link-workspace-packages` skill for setup
+- **CLI stream contract** — stdout contains only the command payload (source,
+  JSON, XML, or other data intended for piping); progress, diagnostics, and
+  errors go to stderr. Source-producing commands must be safe to use as the
+  input of a corresponding write command. Enforce this via a regression test
+  at the shared output/progress abstraction, not in an individual command.
diff --git a/packages/adt-cli/src/lib/shared/adt-client.ts b/packages/adt-cli/src/lib/shared/adt-client.ts
index f3fffbd62..62815d8da 100644
--- a/packages/adt-cli/src/lib/shared/adt-client.ts
+++ b/packages/adt-cli/src/lib/shared/adt-client.ts
@@ -70,10 +70,10 @@ export const silentLogger: Logger = {
  * Console logger - outputs to console (used when enableLogging is true)
  */
 export const consoleLogger: Logger = {
-  trace: (msg: string) => console.debug(msg),
-  debug: (msg: string) => console.debug(msg),
-  info: (msg: string) => console.log(msg),
-  warn: (msg: string) => console.warn(msg),
+  trace: (msg: string) => console.error(msg),
+  debug: (msg: string) => console.error(msg),
+  info: (msg: string) => console.error(msg),
+  warn: (msg: string) => console.error(msg),
   error: (msg: string) => console.error(msg),
   fatal: (msg: string) => console.error(msg),
   child: () => consoleLogger,
diff --git a/packages/adt-cli/src/lib/utils/logger-config.ts b/packages/adt-cli/src/lib/utils/logger-config.ts
index f8c11f25b..ec340bf08 100644
--- a/packages/adt-cli/src/lib/utils/logger-config.ts
+++ b/packages/adt-cli/src/lib/utils/logger-config.ts
@@ -45,6 +45,7 @@ export function createCliLogger(options: LoggerOptions = {}): Logger {
               ignore: 'pid,hostname,time',
               messageFormat: '[{component}] {msg}',
               hideObject: true,
+              destination: 2,
             },
           }
         : undefined,
diff --git a/packages/adt-cli/src/lib/utils/progress-reporter.test.ts b/packages/adt-cli/src/lib/utils/progress-reporter.test.ts
new file mode 100644
index 000000000..c22ee3208
--- /dev/null
+++ b/packages/adt-cli/src/lib/utils/progress-reporter.test.ts
@@ -0,0 +1,55 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { createProgressReporter } from './progress-reporter';
+
+describe('createProgressReporter', () => {
+  const stdout = vi
+    .spyOn(process.stdout, 'write')
+    .mockImplementation(() => true);
+  const stderr = vi
+    .spyOn(process.stderr, 'write')
+    .mockImplementation(() => true);
+
+  afterEach(() => {
+    stdout.mockClear();
+    stderr.mockClear();
+  });
+
+  it('keeps stdout clean and writes compact step/done to stderr', () => {
+    const reporter = createProgressReporter({ compact: true });
+
+    reporter.step('Reading source...');
+    reporter.done();
+
+    expect(stdout).not.toHaveBeenCalled();
+    expect(stderr).toHaveBeenCalledTimes(3);
+    expect(stderr).toHaveBeenNthCalledWith(1, 'Reading source...');
+    expect(stderr).toHaveBeenNthCalledWith(2, '\r\x1b[K');
+    expect(stderr).toHaveBeenNthCalledWith(3, 'Reading source...\n');
+  });
+
+  it('writes compact persist messages to stderr without touching stdout', () => {
+    const reporter = createProgressReporter({ compact: true });
+
+    reporter.step('Reading source...');
+    reporter.persist('Persisted source');
+
+    expect(stdout).not.toHaveBeenCalled();
+    expect(stderr).toHaveBeenCalledTimes(3);
+    expect(stderr).toHaveBeenNthCalledWith(1, 'Reading source...');
+    expect(stderr).toHaveBeenNthCalledWith(2, '\r\x1b[K');
+    expect(stderr).toHaveBeenNthCalledWith(3, 'Persisted source\n');
+  });
+
+  it('writes compact done(finalMessage) to stderr without touching stdout', () => {
+    const reporter = createProgressReporter({ compact: true });
+
+    reporter.step('Reading source...');
+    reporter.done('Finished');
+
+    expect(stdout).not.toHaveBeenCalled();
+    expect(stderr).toHaveBeenCalledTimes(3);
+    expect(stderr).toHaveBeenNthCalledWith(1, 'Reading source...');
+    expect(stderr).toHaveBeenNthCalledWith(2, '\r\x1b[K');
+    expect(stderr).toHaveBeenNthCalledWith(3, 'Finished\n');
+  });
+});
diff --git a/packages/adt-cli/src/lib/utils/progress-reporter.ts b/packages/adt-cli/src/lib/utils/progress-reporter.ts
index 7e7cc1835..5f6427959 100644
--- a/packages/adt-cli/src/lib/utils/progress-reporter.ts
+++ b/packages/adt-cli/src/lib/utils/progress-reporter.ts
@@ -1,7 +1,9 @@
 /**
  * Lightweight progress reporter for CLI output.
  * - Compact mode keeps updates on a single line (overwriting previous text).
- * - Non-compact mode logs through the provided logger (or console).
+ * - Non-compact mode logs through the provided logger (CLI loggers target stderr).
+ * - Progress is written to stderr so stdout stays safe for piping source,
+ *   JSON, XML, and other command payloads.
  *
  * When a logger is provided, progress messages are tagged with { progress: true }.
  */
@@ -54,7 +56,7 @@ export function createProgressReporter(
 
   const clearLine = () => {
     if (open) {
-      process.stdout.write('\r\x1b[K');
+      process.stderr.write('\r\x1b[K');
     }
   };
 
@@ -65,7 +67,7 @@ export function createProgressReporter(
       return;
     }
     clearLine();
-    process.stdout.write(clean);
+    process.stderr.write(clean);
     lastMessage = clean;
     open = true;
     logWithFlag(clean, { transient: true });
@@ -75,7 +77,7 @@ export function createProgressReporter(
     const clean = sanitize(message);
     clearLine();
     if (compact || !logger) {
-      process.stdout.write(`${clean}\n`);
+      process.stderr.write(`${clean}\n`);
     }
     logWithFlag(clean);
     open = false;
@@ -91,10 +93,10 @@ export function createProgressReporter(
     if (compact) {
       if (finalMessage) {
         const clean = sanitize(finalMessage);
-        process.stdout.write(`${clean}\n`);
+        process.stderr.write(`${clean}\n`);
         logWithFlag(clean);
       } else if (open && lastMessage) {
-        process.stdout.write(`${lastMessage}\n`);
+        process.stderr.write(`${lastMessage}\n`);
         logWithFlag(lastMessage);
       }
     } else {