fix(memory): route memory provider tools in sequential dispatch path

[Hygaard]

Summary

Adds memory provider tool routing to the sequential dispatch path in _execute_tool_calls_sequential, which was missing the memory_manager.has_tool() check that already exists in the concurrent path (_invoke_tool).

Fixes #4708

Problem

After setting up the holographic memory provider plugin, calling fact_store or fact_feedback returns {"error": "Unknown tool: fact_store"}.

The root cause: _should_parallelize_tool_batch() returns False for single tool calls (len <= 1), so they always go through the sequential path. The sequential path's elif chain handles todo, session_search, memory, clarify, and delegate_task explicitly, then falls through to handle_function_call() → registry.dispatch() for everything else. Since memory provider tools are registered in MemoryManager._tool_to_provider (not the main tool registry), they get "Unknown tool."

The concurrent path (_invoke_tool) already handles this correctly at line ~5620:

elif self._memory_manager and self._memory_manager.has_tool(function_name):
    return self._memory_manager.handle_tool_call(function_name, function_args)

Changes

1. Add memory_manager routing to sequential path (run_agent.py) — inserted between the delegate_task handler and the handle_function_call fallthrough:

elif self._memory_manager and self._memory_manager.has_tool(function_name):
    function_result = self._memory_manager.handle_tool_call(function_name, function_args)
    ...

2. Add on_memory_write bridge to sequential memory handler (run_agent.py) — the concurrent path already mirrors built-in memory writes to the external provider via on_memory_write(), but the sequential path was missing this. Added the same bridge after the memory_tool() call.

3. Regression tests (tests/test_run_agent.py) — three new tests in TestMemoryProviderSequentialDispatch:

• test_sequential_routes_memory_provider_tool — single fact_store call routes through memory_manager
• test_sequential_memory_write_bridge — built-in memory writes trigger on_memory_write on the provider
• test_sequential_no_memory_manager_falls_through — no provider configured → normal fallthrough

All 224 existing tests pass alongside the 3 new ones.

Note

Filed as issue #4708 first — we're not 100% certain this is a bug vs. a misunderstanding of the architecture. If the sequential path intentionally doesn't route memory provider tools, please let us know and we'll close both.

Bug found by Claude Opus 4.6 running through Hermes Agent during a debugging session.

[Hygaard]

Superseded by #4803 which shipped in v0.7.0. Same fix, same root cause. Closing to keep things tidy.