This commit implements a progressive refactoring of the tool system to support
plugin discovery, scoped loading, and protocol-driven runtime context injection.
Key changes:
- Add Tool ABC metadata (tool_name, _scopes) and ToolContext dataclass for
dependency injection.
- Introduce ToolLoader with pkgutil-based builtin discovery and
entry_points-based third-party plugin loading.
- Add scope filtering (core/subagent/memory) so different contexts load
appropriate tool sets.
- Introduce ContextAware protocol and RequestContext dataclass to replace
hardcoded per-tool context injection in AgentLoop.
- Add RuntimeState / MutableRuntimeState protocols to decouple MyTool from
AgentLoop.
- Migrate all built-in tools to declare scopes and implement create()/enabled()
hooks.
- Migrate MessageTool, SpawnTool, CronTool, and MyTool to ContextAware.
- Refactor AgentLoop to use ToolLoader and protocol-driven context injection.
- Refactor SubagentManager to use ToolLoader(scope="subagent") with per-run
FileStates isolation.
- Register all built-in tools via pyproject.toml entry_points.
- Add comprehensive tests for loader scopes, entry_points, ContextAware,
subagent tools, and runtime state sync.
The previous patch promoted `message` into top-level `required`, which solved
the `add` loop but broke `list` and `remove`: `ToolRegistry.prepare_call`
enforces `required` via `validate_params`, so `cron(action="list")` and
`cron(action="remove", job_id=...)` — both documented in `SKILL.md` — started
failing schema validation with the same "missing required message" shape that
#3113 describes for `add`.
Instead:
- Keep `required=["action"]` so `list`/`remove` stay callable.
- Prefix `message`'s description with `REQUIRED when action='add'.` and
`job_id`'s with `REQUIRED when action='remove'.` so LLMs see the real
per-action contract up front.
- Keep the improved runtime error message from the previous commit for the
case an LLM still omits `message` on `add`.
Also add `tests/cron/test_cron_tool_schema_contract.py` to lock in:
- `list` and `remove` pass schema validation with no `message`
- `add` with `message` passes
- `add` without `message` surfaces the actionable runtime error
- field descriptions carry the REQUIRED hints
- top-level `required` stays `["action"]`
Existing `tests/cron/test_cron_tool_list.py` cases bypass schema validation by
calling `_list_jobs()` / `_remove_job()` directly, which is why CI didn't catch
the regression; the new test goes through `ToolRegistry.prepare_call`.
