fix(router): sync model name changes across replicas

[muraliavarma]

Relevant issues

Fixes #22190

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Type

🐛 Bug Fix

Changes

upsert_deployment() in router.py only compared litellm_params when deciding whether to update an existing deployment during the 30s polling cycle. If only model_name was changed (e.g. via PATCH /model/{id}/update), the comparison returned equal and the update was skipped. This caused model name changes to never propagate to other replicas — only a full restart would fix it.

Fix: Added model_name to the equality check in upsert_deployment() so that name-only changes are detected and the deployment is replaced during the next poll.

Tests added (tests/litellm/test_router_upsert_deployment.py):

• test_upsert_deployment_detects_model_name_change — verifies upsert updates when only model_name changes
• test_upsert_deployment_skips_when_nothing_changed — verifies no unnecessary updates when nothing changed
• test_upsert_deployment_detects_litellm_params_change — verifies existing behavior (param changes) is preserved

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Project	Deployment	Actions	Updated (UTC)
litellm	Ready	Preview, Comment	Feb 27, 2026 3:54pm

[muraliavarma]

@greptileai

[greptile-apps]

Greptile Summary

Fixes a bug where model name changes via PATCH /model/{id}/update were not propagated across proxy replicas. The upsert_deployment() method only compared litellm_params when deciding whether to update during the 30-second polling cycle — this meant name-only changes were silently skipped. The fix adds model_name to the equality check, which is both necessary and sufficient since pricing fields are already synced through litellm_params and comparing model_info timestamps would cause unnecessary churn.

• Bug fix: Added model_name comparison to the no-op guard in Router.upsert_deployment() (litellm/router.py:6771-6776)
• Tests: 3 new regression tests covering name change detection, no-op skip, and existing params-change behavior
• No custom rule violations detected

Confidence Score: 5/5

• This PR is safe to merge — it's a minimal, well-tested bug fix with no risk of regression.
• The change is a single additional condition in an equality check. It correctly fixes the reported issue ([Bug]: Config changes not syncing across 3 replicas with Redis #22190), has comprehensive test coverage for all three comparison scenarios, does not affect the critical request path, and introduces no new dependencies or architectural changes.
• No files require special attention.

Important Files Changed

Filename	Overview
litellm/router.py	Adds model_name comparison to the equality check in upsert_deployment() so that name-only changes are detected during the 30s polling cycle. Correct and minimal fix. One stale comment noted.
tests/litellm/test_router_upsert_deployment.py	New test file with three well-structured regression tests covering: model_name change detection, no-op skip when nothing changed, and existing litellm_params change behavior.

Sequence Diagram

sequenceDiagram
    participant User as Admin User
    participant API as PATCH /model/{id}/update
    participant DB as Database
    participant R1 as Replica 1 (Router)
    participant R2 as Replica 2 (Router)

    User->>API: Update model_name only
    API->>DB: Save updated model_name
    API->>R1: Direct update on handling replica

    Note over R2: 30s polling cycle
    R2->>DB: Fetch all models
    DB-->>R2: Returns model with new name

    alt Before fix
        R2->>R2: Compare litellm_params only
        R2->>R2: Params match → skip update ❌
        Note over R2: Name change lost!
    end

    alt After fix
        R2->>R2: Compare litellm_params AND model_name
        R2->>R2: Name differs → upsert deployment ✅
        Note over R2: Name change propagated!
    end

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Additional Comments (1)

litellm/router.py
Stale comment after logic change
This comment says "if there is a new litellm param" but the condition above now also triggers on model_name changes. Consider updating it to reflect the broader scope.

                # if there is a new litellm param or model name -> then update the deployment