Expand SimEngine API and error-path tests (#44)

[Copilot]

Adds comprehensive test coverage for all public SimEngine APIs and error handling paths.

Tests Added (26 new, 8→34 total)

Initialization & Views

• initialize_state validation (missing args, state before init)
• query_view for all types (summary, snapshot, district, post-mortem)
• Invalid view handling (unknown names, missing/invalid district_id)

APIs

• director_feed structure and population after ticks
• All explanations helpers: query_timeline, explain_metric, explain_faction, explain_agent, explain_district, why
• Progression helpers: progression_summary, calculate_success_chance (with/without agent/faction), agent_roster_summary

Error Paths

• EngineNotInitializedError on premature state access
• ValueError on tick limit exceeded
• ValueError on unknown views

Progression State

• Validates progression updates when ticks advance

class TestErrorPaths:
    def test_advance_ticks_before_initialization_raises(self) -> None:
        engine = SimEngine()
        with pytest.raises(EngineNotInitializedError):
            engine.advance_ticks(1)

    def test_query_view_unknown_raises_valueerror(self) -> None:
        engine = SimEngine()
        engine.initialize_state(world="default")
        with pytest.raises(ValueError, match="Unknown view"):
            engine.query_view("nonexistent")

Original prompt

"Issue 44 - Expand SimEngine API and error-path tests" to test agent

Created from Copilot CLI via the copilot delegate command.

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