GitCheckoutHandler.discover_children() and FsDirectoryHandler.discover_children()
now call discover_devcontainers() after scanning for fs-directory children. Any
.devcontainer/devcontainer.json or root-level .devcontainer.json found at the
resource location is registered as a devcontainer-instance child resource with
provisioning_state: discovered. Named configurations are also discovered and carry
the configuration name in the config_name property.

This wires the previously-isolated discover_devcontainers() function into the
production code path, enabling the spec's zero-configuration devcontainer experience.

ISSUES CLOSED: #4740

@@ -261,6 +265,28 @@ class FsDirectoryHandler(BaseResourceHandler):
             )
             children.append(child)
 
+        # Wire devcontainer auto-discovery (issue #4740)

@@ -346,6 +351,28 @@ class GitCheckoutHandler(BaseResourceHandler):
             )
             children.append(child)
 
+        # Wire devcontainer auto-discovery (issue #4740)

@@ -5,6 +5,19 @@ The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 ## [Unreleased]
 
+### Fixed

@@ -0,0 +252,4 @@
+        ctx.dcwire_error = exc
+
+
+@when("dcwire I call discover_children on the fs-directory resource")

@@ -12,3 +9,1 @@
-- ``list_children`` — ``git ls-tree -r --name-only HEAD``
-- ``diff``  — ``git diff --no-index``
-- ``discover_children`` — ``git ls-tree --name-only HEAD``
+- ``read``  -- ``git show HEAD:<path>``

@@ -36,6 +37,7 @@ from cleveragents.resource.handlers._base import (
     EMPTY_CONTENT_HASH,
     BaseResourceHandler,
 )
+from cleveragents.resource.handlers.discovery import discover_devcontainers