[IMPROVEMENT] Single source of truth for LLM context window sizes

Feature Area

Core functionality

Is your feature request related to an existing bug? Please link it here.

Related: #7303 (o1 / o1-pro / o3 fall back to the 8k default because they are missing from some of the duplicated tables). That class of bug is what this issue is meant to stop.

Describe the solution you'd like

Context window sizes are hardcoded in six places. Adding or updating a model means editing llm.py and the native provider (and sometimes Azure or Bedrock too). The copies have already drifted.

Current maps

OpenAI / Azure / Gemini import LLM_CONTEXT_WINDOW_SIZES only to validate bounds, then ignore it and use a local dict.

Known drift (fix these as part of the merge)

• Native OpenAI has gpt-5 / gpt-5-mini / gpt-5-nano (1,047,576). LiteLLM gpt-5 falls through to 8192.
• Native Anthropic has 1M models (claude-sonnet-4-6, claude-opus-5, …) that llm.py does not list as bare Claude ids.
• Native Bedrock prefix anthropic.claude-sonnet-4 is 200k, so anthropic.claude-sonnet-4-6 (1M) gets 200k on the native path.
• OpenAI-compatible (deepseek/…, openrouter/…) inherits OpenAI’s local map, so LiteLLM-only keys like deepseek-chat become 8192.

Lookup rules also disagree: native providers first-match (keys inserted longest-first); llm.py last-match-wins.

Suggested implementation (good first issue)

One module owns lookup + constants. Provider files only declare their prefixes.

1. Add lib/crewai/src/crewai/llms/context_window.py

   • CONTEXT_WINDOW_USAGE_RATIO (0.85), DEFAULT_CONTEXT_WINDOW_SIZE (8192), MIN_CONTEXT, MAX_CONTEXT
   • resolve_context_window_size(model, sizes, *, default, extra_names=()) — longest prefix wins, then apply the 0.85 ratio; validate bounds once
   • Family maps (source of truth for sizes):
     • OPENAI_CONTEXT_WINDOWS — GPT / o-series (OpenAI + Azure)
     • AZURE_CONTEXT_WINDOWS — Azure-only extras (gpt-35-turbo, text-embedding)
     • ANTHROPIC_CONTEXT_WINDOWS — bare claude-* prefixes
     • GEMINI_CONTEXT_WINDOWS
     • BEDROCK_CONTEXT_WINDOWS — Titan, Nova, Llama, etc.
     • LITELLM_CONTEXT_WINDOWS — Groq / Mistral / Together / other LiteLLM-only ids currently in llm.py
   • Expand Bedrock Claude ids from ANTHROPIC_CONTEXT_WINDOWS (anthropic., us.anthropic., eu.anthropic., apac.anthropic., global.anthropic.) so a new Claude window is added once
   • LLM_CONTEXT_WINDOW_SIZES = merge of the above (LiteLLM + OpenAI-compatible)

2. Rewire providers — delete the local context_windows dicts. get_context_window_size becomes a one-liner against that provider’s map. Keep today’s defaults: OpenAI/Azure/Bedrock 8192, Anthropic 200k, Gemini 1M.

3. Re-export from lib/crewai/src/crewai/llm.py

   • LLM_CONTEXT_WINDOW_SIZES, CONTEXT_WINDOW_USAGE_RATIO, DEFAULT_CONTEXT_WINDOW_SIZE so existing tests (patch.dict("crewai.llm.LLM_CONTEXT_WINDOW_SIZES", …)) keep working.
   • LiteLLM get_context_window_size calls the shared resolver with the merged map and _context_window_model_name().

4. Do not change base_llm.DEFAULT_CONTEXT_WINDOW_SIZE = 4096 (custom LLM fallback). That is a different default.

After this, adding gpt-5.7 is one entry in OPENAI_CONTEXT_WINDOWS. Native OpenAI, Azure, LiteLLM, and OpenAI-compatible all pick it up. Adding claude-sonnet-4-7 is one Anthropic entry; Bedrock regional ids are generated.

Acceptance criteria

• One module owns raw window sizes and longest-prefix lookup. Provider completion files do not copy the full list.
• Adding a GPT / Claude / Gemini model is a single map entry (plus Bedrock prefix expansion for Claude).
• crewai.llm still exports LLM_CONTEXT_WINDOW_SIZES, CONTEXT_WINDOW_USAGE_RATIO, and DEFAULT_CONTEXT_WINDOW_SIZE.
• Existing tests stay green: lib/crewai/tests/test_llm.py, llms/openai/test_openai.py, llms/azure/test_azure.py, llms/anthropic/test_anthropic.py.
• New unit tests for resolve_context_window_size (longest prefix, bounds, default).
• Parity: same family id via native vs is_litellm=True returns the same window (gpt-5, claude-sonnet-4-6, gemini-2.0-flash).
• LLM(model="bedrock/anthropic.claude-sonnet-4-6").get_context_window_size() is int(1_000_000 * CONTEXT_WINDOW_USAGE_RATIO) (not 200k).
• LiteLLM gpt-5 uses the native 1,047,576 window, not 8192. gpt-5.4-mini stays 200k.

Describe alternatives you've considered

• Keep one giant dict in llm.py and have every provider call it. That is still one source of truth, but provider files would not own only the models they need, and Azure/Bedrock extras get mixed into the OpenAI/Anthropic lists.
• Fetch windows at runtime from LiteLLM’s model_prices_and_context_window.json. The CLI already references that URL; it is not used at runtime today and would add a network dependency. Out of scope.

Additional context

• Do not change frozen docs under docs/v*/.
• Follow AGENTS.md: keep the diff small; write tests for behavior (lookup + parity), not implementation details.