feat: add command output capture to troubleshooting sessions (#57)

Engineers can now paste command output during action steps. Output is
stored in the session decisions JSONB, displayed in session review,
included in all 4 export formats with command context, and preserved
in session-to-tree conversions.

- Collapsible "Paste Output" textarea on action nodes with commands
- 10,000 character limit with live character count
- Works on both built-in and custom action steps
- Preloads output when revisiting a step via Go Back
- All exports show commands run alongside captured output

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/services/export_service.py

@@ -81,6 +81,30 @@ def _get_step_duration_seconds(decision: dict[str, Any]) -> int | None:
     return None
 
 
+def _get_command_output(decision: dict[str, Any]) -> str | None:
+    """Extract and normalize command_output from a decision dict."""
+    output = decision.get("command_output")
+    if not isinstance(output, str):
+        return None
+    output = output.strip()
+    return output if output else None
+
+
+def _find_node_commands(tree_snapshot: dict[str, Any], node_id: str) -> list[str]:
+    """Find the commands list for a node in the tree snapshot."""
+    def _search(node: dict[str, Any]) -> list[str] | None:
+        if node.get("id") == node_id:
+            return node.get("commands") or []
+        for child in node.get("children", []):
+            result = _search(child)
+            if result is not None:
+                return result
+        return None
+
+    structure = tree_snapshot.get("tree_structure") or tree_snapshot
+    return _search(structure) or []
+
+
 def _get_outcome_label(session: Session) -> str | None:
     """Map stored outcome enum to human-friendly label."""
     outcome = getattr(session, "outcome", None)
@@ -137,6 +161,14 @@ def generate_markdown_export(session: Session, options: SessionExport) -> str:
             lines.append(f"**Answer:** {answer}")
         if notes:
             lines.append(f"**Notes:** {notes}")
+        if command_output := _get_command_output(decision):
+            commands = _find_node_commands(session.tree_snapshot, decision.get("node_id", ""))
+            if commands:
+                lines.append(f"**Commands Run:** {', '.join(f'`{c}`' for c in commands)}")
+            lines.append("**Output:**")
+            lines.append("```")
+            lines.append(command_output)
+            lines.append("```")
         if duration_seconds is not None:
             lines.append(f"**Duration:** {_format_step_duration(duration_seconds)}")
         if options.include_timestamps and decision.get("timestamp"):
@@ -190,6 +222,13 @@ def generate_text_export(session: Session, options: SessionExport) -> str:
             lines.append(f"   Answer: {answer}")
         if notes:
             lines.append(f"   Notes: {notes}")
+        if command_output := _get_command_output(decision):
+            commands = _find_node_commands(session.tree_snapshot, decision.get("node_id", ""))
+            if commands:
+                lines.append(f"   Commands Run: {', '.join(commands)}")
+            lines.append("   Output:")
+            for output_line in command_output.splitlines():
+                lines.append(f"     {output_line}")
         if duration_seconds is not None:
             lines.append(f"   Duration: {_format_step_duration(duration_seconds)}")
 
@@ -253,6 +292,12 @@ def generate_html_export(session: Session, options: SessionExport) -> str:
             html_parts.append(f'<p class="answer">Answer: {answer}</p>')
         if notes:
             html_parts.append(f'<p class="notes">Notes: {notes}</p>')
+        if command_output := _get_command_output(decision):
+            commands = _find_node_commands(session.tree_snapshot, decision.get("node_id", ""))
+            if commands:
+                cmd_html = ", ".join(f"<code>{html.escape(c)}</code>" for c in commands)
+                html_parts.append(f'<p><strong>Commands Run:</strong> {cmd_html}</p>')
+            html_parts.append(f'<pre><code>{html.escape(command_output)}</code></pre>')
         if duration_seconds is not None:
             html_parts.append(f'<p class="duration"><strong>Duration:</strong> {_format_step_duration(duration_seconds)}</p>')
         if options.include_timestamps and decision.get("timestamp"):
@@ -304,6 +349,13 @@ def generate_psa_export(session: Session, options: SessionExport) -> str:
             lines.append(line)
             if notes:
                 lines.append(f"   Notes: {notes}")
+            if command_output := _get_command_output(decision):
+                commands = _find_node_commands(session.tree_snapshot, decision.get("node_id", ""))
+                if commands:
+                    lines.append(f"   Commands: {', '.join(commands)}")
+                lines.append("   Output:")
+                for output_line in command_output.splitlines():
+                    lines.append(f"     {output_line}")
     else:
         lines.append("No steps recorded.")
     lines.append("")