fix(providers): add ProviderType.GEMINI to ProviderRegistry.FALLBACK_ORDER

Add GEMINI to the provider fallback chain so Gemini-only users can get a
default provider via auto-discovery without setting GOOGLE_API_KEY. The
GEMINI enum value, capabilities, default model, and API key mapping were
already defined but the type was missing from both ProviderRegistry.FALLBACK_ORDER
and FallbackSelector.DEFAULT_FALLBACK_ORDER.

Also convert the TDD @tdd_expected_fail regression test to a permanent guard
by removing the inversion tag since the bug is fixed.

ISSUES CLOSED: #10906

CHANGELOG.md

@@ -7,6 +7,20 @@ The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 ### Fixed
 
+- **ProviderType.GEMINI missing from ProviderRegistry.FALLBACK_ORDER** (#10906, #4750):
+  Added `ProviderType.GEMINI` to both `ProviderRegistry.FALLBACK_ORDER` (after
+  `ProviderType.GOOGLE`) and `FallbackSelector.DEFAULT_FALLBACK_ORDER` (after
+  `"google"`). The GEMINI enum value, capabilities, default model, and API key mapping
+  were already defined in the registry but Gemini-only users could not get a provider
+  via the fallback chain — `get_default_provider_type()` returned ``None`` when only
+  ``GEMINI_API_KEY`` was set. Also removed the ``@tdd_expected_fail`` tag from the
+  Behave regression test (`features/tdd_gemini_fallback_order_4750.feature`) since the
+  bug is now resolved and the test must pass normally.
+
+### Fixed
+
+- **Cross-actor subgraph cycle detection reads actor_ref field** (#1431): Fixed
+
 - **Cross-actor subgraph cycle detection reads actor_ref field** (#1431): Fixed
   `_detect_subgraph_cycles()`, `_map_node()`, and the `compile_actor()` main loop
   in `src/cleveragents/actor/compiler.py` to read `actor_ref` from the top-level

CONTRIBUTORS.md

@@ -31,3 +31,4 @@ Below are some of the specific details of various contributions.
 * HAL 9000 has contributed comprehensive milestone documentation for v3.6.0 (Advanced Concepts & Deferred Features) and v3.7.0 (TUI Implementation) (PR #9903): split into sub-documents covering context strategies, LLM backends, resource types, A2A rename, container tool execution, scope chain resolution, cost/safety budgets, E2E workflow tests, code review examples, plugin architecture, TUI layout, persona system, reference/command input, session management, configuration, and TuiMaterializer integration.
 * HAL 9000 has contributed the LLMTraceRepository data-integrity fix (PR #8185 / issue #7505): replaced the unconditional `session.commit()` in `LLMTraceRepository.save()` with a dual-path implementation that respects the UnitOfWork pattern — flushing only when an external session is provided, and flushing + committing + closing when operating standalone. This eliminates premature transaction commits, loss of rollback capability, and a docstring/implementation mismatch.
 * HAL 9000 has contributed the ACMS Index Data Model and File Traversal Engine (PR #9664 / issue #9579): foundational data structures for indexed context entries with hot/warm/cold/archive storage tier classification, tag system, and a timeout-safe chunked file traversal engine for large projects with 10,000+ files.
+* HAL 9000 has contributed the ProviderType.GEMINI fallback order fix (PR #10906 / issue #4750): added GEMINI to both ProviderRegistry.FALLBACK_ORDER and FallbackSelector.DEFAULT_FALLBACK_ORDER so Gemini-only users can get a default provider via the fallback chain, and converted the TDD @tdd_expected_fail regression test to a permanent guard.

features/steps/tdd_gemini_fallback_order_4750_steps.py

@@ -2,14 +2,15 @@
 
 Issue: #4750 — ProviderType.GEMINI missing from ProviderRegistry.FALLBACK_ORDER
 TDD Issue: #10896
+Fixed by: PR #10906
 
-This test captures the bug: when only GEMINI_API_KEY is set (without GOOGLE_API_KEY),
-get_default_provider_type() returns None instead of ProviderType.GEMINI because
-GEMINI is absent from FALLBACK_ORDER.
+This test captures the regression that was fixed when ProviderType.GEMINI was added
+to both ProviderRegistry.FALLBACK_ORDER and FallbackSelector.DEFAULT_FALLBACK_ORDER.
+Previously, get_default_provider_type() returned None instead of ProviderType.GEMINI
+when only GEMINI_API_KEY was set (without GOOGLE_API_KEY) because GEMINI was absent
+from FALLBACK_ORDER.
 
-The @tdd_expected_fail tag inverts the result so CI passes while the bug exists.
-Once the fix is applied (adding ProviderType.GEMINI to FALLBACK_ORDER), the
-@tdd_expected_fail tag must be removed and the test must pass normally.
+The @tdd_expected_fail tag has been removed — this is now a permanent regression guard.
 """
 
 from __future__ import annotations

features/tdd_gemini_fallback_order_4750.feature

@@ -3,7 +3,7 @@ Feature: TDD: ProviderType.GEMINI missing from ProviderRegistry.FALLBACK_ORDER
   I want get_default_provider_type() to return ProviderType.GEMINI via the fallback chain
   So that Gemini-only users can use auto-discovery without setting GOOGLE_API_KEY
 
-  @tdd_issue @tdd_issue_4750 @tdd_expected_fail
+  @tdd_issue @tdd_issue_4750
   Scenario: Gemini-only user gets GEMINI as default provider via fallback order
     Given a ProviderRegistry configured with only gemini_api_key set
     And CLEVERAGENTS_DEFAULT_PROVIDER is not set for tdd test

src/cleveragents/providers/fallback_selector.py

@@ -64,6 +64,7 @@ class FallbackSelector:
         "openai",
         "anthropic",
         "google",
+        "gemini",
         "azure",
         "openrouter",
         "groq",

src/cleveragents/providers/registry.py

@@ -220,6 +220,7 @@ class ProviderRegistry:
         ProviderType.OPENAI,
         ProviderType.ANTHROPIC,
         ProviderType.GOOGLE,
+        ProviderType.GEMINI,
         ProviderType.AZURE,
         ProviderType.OPENROUTER,
         ProviderType.GROQ,