feat: add Fireworks context length detection support

- Add api.fireworks.ai to _URL_TO_PROVIDER for automatic provider detection
- Add fireworks to PROVIDER_TO_MODELS_DEV mapped to 'fireworks-ai' (the
  correct models.dev provider key — original PR used 'fireworks' which
  would silently fail the lookup)

Co-authored-by: sroecker <sroecker@users.noreply.github.com>
Cherry-picked from PR #3989 with models.dev key fix.

agent/model_metadata.py

@@ -176,6 +176,7 @@ _URL_TO_PROVIDER: Dict[str, str] = {
     "api.deepseek.com": "deepseek",
     "api.githubcopilot.com": "copilot",
     "models.github.ai": "copilot",
+    "api.fireworks.ai": "fireworks",
 }
 
 

agent/models_dev.py

@@ -43,6 +43,7 @@ PROVIDER_TO_MODELS_DEV: Dict[str, str] = {
     "opencode-zen": "opencode",
     "opencode-go": "opencode-go",
     "kilocode": "kilo",
+    "fireworks": "fireworks-ai",
 }