feat: harden Python workflow and structured planning

Replace the uv-specific skill with a portable Python skill and rewrite the default user system prompt as a concise, structured Markdown execution policy.

Normalize a single fenced structured-JSON response, retry invalid skill selection with think disabled, validate selected skill output, and make coding plans keep editing and verification in one task.

Document the file_edit patch payload, expose that contract in the tool catalog, and convert malformed patch input into a retryable tool failure instead of terminating the agent task.

Update configuration and runtime tests for the Python skill, exact tool catalog, structured-output retry, and implementation-and-verification planning guidance.

Verified with 82 Agent.Core tests and an agent-mcp Python scheduling scenario with 49 passing unittest cases.

1 files changed, 3 insertions, 3 deletions

diff --git a/tests/Agent.Core.Tests/ConfigurationTests.cs b/tests/Agent.Core.Tests/ConfigurationTests.cs
index f6db9f2..64b2d85 100644
--- a/tests/Agent.Core.Tests/ConfigurationTests.cs
+++ b/tests/Agent.Core.Tests/ConfigurationTests.cs
@@ -139,14 +139,14 @@ public sealed class ConfigurationTests
         // Legacy single markdown — should be ignored (not loaded).
         directory.File("skills/legacy.md", "legacy skill");
         // Standard skill directory with frontmatter.
-        directory.File("skills/python-via-uv/SKILL.md", "---\nname: python-via-uv\ndescription: Python execution skill.\n---\n# Python via uv\nInstructions here.");
+        directory.File("skills/python/SKILL.md", "---\nname: python\ndescription: Python execution skill.\n---\n# Python\nInstructions here.");
         // Non-SKILL.md files in skill directory should not be loaded as skills.
-        directory.File("skills/python-via-uv/reference.md", "must not be loaded as a skill");
+        directory.File("skills/python/reference.md", "must not be loaded as a skill");
 
         var skills = SkillLoader.Load(Path.Combine(directory.Path, "skills"));
 
         Assert.Single(skills);
-        Assert.Equal("python-via-uv", skills[0].Name);
+        Assert.Equal("python", skills[0].Name);
         Assert.Equal("Python execution skill.", skills[0].Description);
         Assert.Contains("Instructions here.", skills[0].Instructions);
     }