fix(shell): timeout is recoverable + coaches detach, not a workflow kill

A foreground long-running command (npm run dev, vite, a --watch task) hit
the 30s timeout and returned recoverable=false, giving the stage no
transition to take -> WorkflowFailed "no transition condition matched"
(killed session d734e1de). A non-zero exit right below already returns
recoverable=true; a timeout is no more fatal. Return recoverable and coach
the model to start the process detached (nohup ... &) and verify separately,
or run a one-shot that exits. No background-process registry: the model
backgrounds it itself via `&`, which already routes through `sh -c`.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HMbPmZZjcXhR2crU82zZ8S

infrastructure/tools/src/main/kotlin/com/correx/infrastructure/tools/shell/ShellTool.kt

@@ -293,10 +293,20 @@ class ShellTool(
             killTree(process)
             stdoutDeferred.cancel()
             stderrDeferred.cancel()
+            // A timeout is NOT fatal — it's usually a long-running/watch/server command (npm run dev,
+            // vite, a watcher) run in the foreground, where it never exits. Return recoverable so the
+            // stage keeps going and coach the model to detach it, instead of killing the workflow with
+            // a dead-end failure (no transition matched). ponytail: no background-process registry —
+            // the model backgrounds it itself via `&`/nohup, which already routes through `sh -c`.
             return@coroutineScope ToolResult.Failure(
                 invocationId = request.invocationId,
-                reason = "Process timed out after ${timeoutMs}ms",
-                recoverable = false,
+                reason = "Process did not exit within ${timeoutMs}ms and was killed. If this is a " +
+                    "long-running command (a dev server, `npm run dev`/`vite`/`serve`, a `--watch` " +
+                    "task), start it detached so it returns immediately — e.g. " +
+                    "`nohup <cmd> > /tmp/dev.log 2>&1 &` — then verify separately (curl the port, or " +
+                    "read the log). If you only needed its output, run a one-shot command that exits " +
+                    "(e.g. `npm run build`, not `npm run dev`).",
+                recoverable = true,
             )
         }
         val exitCode = process.exitValue()

infrastructure/tools/src/test/kotlin/com/correx/infrastructure/tools/shell/ShellToolTest.kt

@@ -155,8 +155,9 @@ class ShellToolTest {
 
         assertTrue(result is ToolResult.Failure)
         val failure = result as ToolResult.Failure
-        assertEquals("Process timed out after 100ms", failure.reason)
-        assertFalse(failure.recoverable)
+        assertTrue(failure.reason.contains("did not exit within 100ms"), failure.reason)
+        assertTrue(failure.reason.contains("detached"), "must coach the model to background it")
+        assertTrue(failure.recoverable, "a timeout is a long-running command, not a fatal error")
     }
 
     @Test