core/config: split agent system_prompt and tool_directives

tests/test_config/test_agent_section.py

@@ -2,7 +2,12 @@ from __future__ import annotations
 
 from typing import TYPE_CHECKING
 
-from plyngent.config import DEFAULT_SYSTEM_PROMPT, load
+from plyngent.config import (
+    DEFAULT_SYSTEM_PROMPT,
+    DEFAULT_TOOL_DIRECTIVES,
+    compose_agent_system_content,
+    load,
+)
 
 if TYPE_CHECKING:
     from pathlib import Path
@@ -13,7 +18,9 @@ def test_agent_section_defaults(tmp_path: Path) -> None:
     _ = path.write_text("", encoding="utf-8")
     store = load(path)
     assert store.agent_config.system_prompt == DEFAULT_SYSTEM_PROMPT
+    assert store.agent_config.tool_directives == DEFAULT_TOOL_DIRECTIVES
     assert "professional coding agent" in store.agent_config.system_prompt
+    assert "### Workspace" in store.agent_config.tool_directives
     assert store.agent_config.max_tool_result_chars == 32_000
     assert store.agent_config.parallel_tools is True
     assert store.agent_config.confirm_destructive is True
@@ -21,12 +28,31 @@ def test_agent_section_defaults(tmp_path: Path) -> None:
     assert store.agent_config.max_context_tokens == 200_000
 
 
+def test_compose_defaults_join_persona_and_directives() -> None:
+    body = compose_agent_system_content(DEFAULT_SYSTEM_PROMPT, DEFAULT_TOOL_DIRECTIVES)
+    assert body is not None
+    assert body.startswith("You are a professional coding agent")
+    assert "\n\n### Workspace" in body
+    assert "### Todos" in body
+    # No double-blank-line collapse issues between parts.
+    assert "\n\n\n" not in body
+
+
+def test_compose_empty_combinations() -> None:
+    assert compose_agent_system_content("", "") is None
+    assert compose_agent_system_content("  ", "\n") is None
+    assert compose_agent_system_content("Only persona", "") == "Only persona"
+    assert compose_agent_system_content("", "Only tools") == "Only tools"
+    assert compose_agent_system_content("Persona", "Tools") == "Persona\n\nTools"
+
+
 def test_agent_section_parse(tmp_path: Path) -> None:
     path = tmp_path / "c.toml"
     _ = path.write_text(
         """
 [agent]
 system_prompt = "Be brief."
+tool_directives = "Use tools carefully."
 max_tool_result_chars = 100
 parallel_tools = false
 confirm_destructive = false
@@ -37,14 +63,20 @@ max_context_tokens = 5000
     )
     store = load(path)
     assert store.agent_config.system_prompt == "Be brief."
+    assert store.agent_config.tool_directives == "Use tools carefully."
     assert store.agent_config.max_tool_result_chars == 100
     assert store.agent_config.parallel_tools is False
     assert store.agent_config.confirm_destructive is False
     assert store.agent_config.path_denylist == ["/secrets/", ".ssh/"]
     assert store.agent_config.max_context_tokens == 5000
+    composed = compose_agent_system_content(
+        store.agent_config.system_prompt,
+        store.agent_config.tool_directives,
+    )
+    assert composed == "Be brief.\n\nUse tools carefully."
 
 
-def test_agent_system_prompt_empty_disables(tmp_path: Path) -> None:
+def test_agent_system_prompt_empty_disables_persona_only(tmp_path: Path) -> None:
     path = tmp_path / "c.toml"
     _ = path.write_text(
         """
@@ -55,3 +87,52 @@ system_prompt = ""
     )
     store = load(path)
     assert store.agent_config.system_prompt == ""
+    assert store.agent_config.tool_directives == DEFAULT_TOOL_DIRECTIVES
+    body = compose_agent_system_content(
+        store.agent_config.system_prompt,
+        store.agent_config.tool_directives,
+    )
+    assert body is not None
+    assert "### Workspace" in body
+    assert "professional coding agent" not in body
+
+
+def test_agent_tool_directives_empty_disables_playbook_only(tmp_path: Path) -> None:
+    path = tmp_path / "c.toml"
+    _ = path.write_text(
+        """
+[agent]
+tool_directives = ""
+""",
+        encoding="utf-8",
+    )
+    store = load(path)
+    assert store.agent_config.tool_directives == ""
+    assert store.agent_config.system_prompt == DEFAULT_SYSTEM_PROMPT
+    body = compose_agent_system_content(
+        store.agent_config.system_prompt,
+        store.agent_config.tool_directives,
+    )
+    assert body is not None
+    assert "professional coding agent" in body
+    assert "### Workspace" not in body
+
+
+def test_agent_both_empty_disables_system(tmp_path: Path) -> None:
+    path = tmp_path / "c.toml"
+    _ = path.write_text(
+        """
+[agent]
+system_prompt = ""
+tool_directives = ""
+""",
+        encoding="utf-8",
+    )
+    store = load(path)
+    assert (
+        compose_agent_system_content(
+            store.agent_config.system_prompt,
+            store.agent_config.tool_directives,
+        )
+        is None
+    )