[Docs] Add LITELLM_MAX_BUDGET_PER_SESSION_TTL to env vars reference

[yuneng-jiang]

Summary

Failure Path (Before Fix)

The test_env_keys CI check scans all Python files for os.getenv() and litellm.get_secret() calls, then verifies each key is documented in config_settings.md. The new max_budget_per_session_limiter.py uses LITELLM_MAX_BUDGET_PER_SESSION_TTL but it was not added to the docs table.

Fix

Add LITELLM_MAX_BUDGET_PER_SESSION_TTL to the environment variables reference table in config_settings.md.

Testing

• test_env_keys.py should pass with this env var now documented

Type

📖 Documentation

[vercel]

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Project	Deployment	Actions	Updated (UTC)
litellm	Building	Preview, Comment	Mar 9, 2026 9:40pm

[greptile-apps]

Greptile Summary

This is a minimal, docs-only PR that adds one missing row to the environment variables reference table in config_settings.md for LITELLM_MAX_BUDGET_PER_SESSION_TTL. The entry was absent, causing the test_env_keys CI check to fail because it detected the env var being consumed in max_budget_per_session_limiter.py but found no matching documentation.

• The new row is inserted in correct alphabetical order (between LITELLM_MASTER_KEY and LITELLM_MAX_ITERATIONS_TTL).
• The description ("TTL in seconds for session budget counters used by the max-budget-per-session limiter") accurately reflects the variable's usage in _PROXY_MaxBudgetPerSessionHandler.__init__.
• The documented default of 3600 matches DEFAULT_MAX_BUDGET_PER_SESSION_TTL = 3600 in the implementation.
• No code changes are introduced; there is no risk of behavioral regression.

Confidence Score: 5/5

• This PR is safe to merge — it is a documentation-only change with no code modifications.
• The single changed line is a documentation table entry. The variable name, description, and default value all accurately match the implementation in max_budget_per_session_limiter.py. No logic, configuration, or API surface is altered.
• No files require special attention.

Important Files Changed

Filename	Overview
docs/my-website/docs/proxy/config_settings.md	Adds a single documentation row for LITELLM_MAX_BUDGET_PER_SESSION_TTL in alphabetical order between LITELLM_MASTER_KEY and LITELLM_MAX_ITERATIONS_TTL; description and default value accurately reflect the implementation in max_budget_per_session_limiter.py.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Proxy Startup] -->|reads env var| B["os.getenv('LITELLM_MAX_BUDGET_PER_SESSION_TTL', 3600)"]
    B --> C[_PROXY_MaxBudgetPerSessionHandler.__init__]
    C --> D{Redis available?}
    D -->|Yes| E[Register Lua atomic-increment script]
    D -->|No| F[In-memory fallback]
    E --> G[async_pre_call_hook: check session spend ≥ max_budget?]
    F --> G
    G -->|Yes| H[Raise HTTP 429]
    G -->|No| I[Allow request]
    I --> J[async_log_success_event: increment session spend by response_cost]
    J -->|TTL applied on first write| K[Cache key expires after TTL seconds]

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_{Last reviewed commit: b4e78ac}