feat(mm-routing): add Kimi K3 support

[krishung5]

Summary

• bump llm-multimodal to 1.9.0 and llm-tokenizer to 1.6.0 for Kimi-K3 model-family support
• make routing-side image expansion match Kimi-K3's backend prompt shape: <|media_begin|>image {width}x{height}<|media_content|>...<|media_end|>
• retain repeated-pad expansion for Kimi-K2.5/Kimi-K2.6 and other existing model families
• disable exact MM routing conservatively if K3 control tokens cannot be resolved atomically

Closes DIS-2566

Validation

• cargo fmt --all -- --check
• cargo test -p dynamo-llm --features mm-routing --lib kimi_k3_ — 7 passed
• cargo test -p dynamo-llm --features mm-routing --lib kimi_k2_ — 2 passed
• Kimi-K3, two TP8 vLLM workers:
  • distinct seeds routed to different workers
  • image A replay returned to its seed worker with 3/4 blocks overlap and 2304 backend-cached tokens
  • image B replay returned to its seed worker with 1/2 blocks overlap and 768 backend-cached tokens
• Kimi-K3, two TP8 SGLang workers:
  • distinct seeds routed to different workers
  • image A replay returned to its seed worker with 47/48 blocks overlap and 3008 backend-cached tokens
  • image B replay returned to its seed worker with 20/21 blocks overlap and 1280 backend-cached tokens
• all eight end-to-end responses completed successfully with 64 completion tokens; no OOMs or runtime errors

The broad crate test run reached the HF-backed integration suite; its parallel preprocessor cases encountered shared cache lock contention. A serial rerun passed 23/24 cases, with the remaining unrelated Llama continuation snapshot differing after an optional Hugging Face template fetch returned 404. No generated snapshot update is included here.

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Summary by CodeRabbit

• New Features

  • Added support for Kimi-K3 multimodal image prompts, including media wrapper tokens and image dimensions.
  • Improved image-token routing for supported multimodal models while preserving existing behavior for Kimi-K2.
  • Added model-specific handling for image prompt formats.

• Bug Fixes

  • Improved multimodal routing reliability when model control tokens cannot be resolved.

[devin-ai-integration]

Devin Review found 5 potential issues.

[coderabbitai]

Walkthrough

The change updates dependency versions and adds model-specific MM routing for Kimi-K3. Routing metadata now identifies Kimi-K3 prompt shapes, resolves control tokens, and expands image routing tokens with wrapper and dimension tokens.

Changes

Kimi-K3 multimodal routing

Layer / File(s)	Summary
Classify model image prompt shapes lib/llm/src/preprocessor/lightseek_mm.rs	Image-token resolution now returns the token ID and ImagePromptKind. Kimi-K3 uses Kimi3; other models retain RepeatedPad. Tests cover Kimi-K3 and Kimi-K2.
Resolve routing prompt layouts lib/llm/src/preprocessor.rs, Cargo.toml, lib/llm/Cargo.toml	The preprocessor resolves Kimi-K3 control tokens and stores the routing image prompt layout. Dependency pins update velo, tokio, mio, llm-multimodal, and llm-tokenizer.
Expand per-image routing tokens lib/llm/src/preprocessor.rs	MM routing emits Kimi-K3 media wrapper tokens, tokenized image dimensions, and pad-filled bodies. Other models retain repeated-pad expansion. Tests cover replacement output and invalid control-token encodings.

Estimated code review effort: 3 (Moderate) | ~30 minutes

Merge Risk: 🟡 Moderate · up to 905a5

When image-token accounting is unavailable, the change can still send image-specific cache metadata while routing by text prefix, causing requests to miss their intended worker affinity and reducing or misaligning cache reuse. Merge should wait for this bounded correctness issue to be fixed or explicitly accepted.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely identifies the main change: adding Kimi K3 support to MM routing.
Description check	✅ Passed	The description explains the changes, validation, results, and related issue, although it does not use all template headings.

✨ Finishing Touches 💡 1

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[coderabbitai]

Actionable comments posted: 1

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Inline comments:
In `@lib/llm/src/preprocessor.rs`:
- Around line 1601-1607: Update the routing token tuple around
routing_image_token_id so that image-token routing is retained only when both
prompt_layout and image_token_counter (counter) are present. Preserve the
existing prompt_layout gating and ensure the downstream routing mode cannot
receive routing_image_token_id when counter is None.

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ℹ️ Review info

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Run ID: bfe59b8c-75ea-46ba-acfb-19c23c4eb497

📥 Commits

Reviewing files that changed from the base of the PR and between f6f9969 and 905a567.

⛔ Files ignored due to path filters (1)

• Cargo.lock is excluded by !**/*.lock

📒 Files selected for processing (4)

• Cargo.toml
• lib/llm/Cargo.toml
• lib/llm/src/preprocessor.rs
• lib/llm/src/preprocessor/lightseek_mm.rs

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[furionw]

Thanks for working on this, @krishung5 . How did you e2e test this?

Did you take dependency on vLLM 0.27? (e.g. #13059)

[krishung5]

Thanks for working on this, @krishung5 . How did you e2e test this?

Did you take dependency on vLLM 0.27? (e.g. #13059)

@furionw For e2e:

1. Started two Kimi-K3 workers, each TP8.
2. Sent requests in this order: image A, image B, image A again, image B again.
3. Verified:

• Repeated image A returned to worker A.
• Repeated image B returned to worker B.
• A and B selected different workers.
• Second requests showed non-zero router overlap and cached tokens.
• Every response completed successfully with 64 output tokens.

My branch was based on ToT main at the time, so I don't think it took vllm 0.27. Is there any fixes in vllm 0.27 that we need to take for K3?

[github-actions]

🌿 Fern Docs Preview: https://nvidia-preview-01a01d85-0284-742a-8343-202a66d464f7.docs.buildwithfern.com/dynamo/dev

[nv-anants]

approving version changes

[jthomson04]

Please also address these existing P2 threads before approval:

• Worker/frontend readiness: the worker helper still does not apply the frontend fastokens and K3 control-token encoding gates.
• K3 EXIF orientation: the vLLM URL-passthrough path still needs the agreed handling.

I did not repeat these as new inline comments.

[krishung5]

Please also address these existing P2 threads before approval:

• Worker/frontend readiness: the worker helper still does not apply the frontend fastokens and K3 control-token encoding gates.
• K3 EXIF orientation: the vLLM URL-passthrough path still needs the agreed handling.

I did not repeat these as new inline comments.

Both addressed in 05bb233.

• Worker/frontend readiness: Exact routing now requires a frontend-issued MM hash marker; native vLLM UUIDs are ignored, so worker normalization cannot run when the frontend falls back.
• K3 EXIF orientation: EXIF-adjusted dimensions are limited to Kimi-K3 with vLLM URL passthrough. SGLang and frontend-decoded images keep their existing behavior. Added an oriented-JPEG regression test.

[datadog-official]

⚠️ Warnings

🧪 1 Test failed in 1 job

Post-Merge CI Pipeline | test — ❌ 1 test failed

View in GitHub Actions

❌ TestConsolidatorRouterE2E::test_remove_deduplication_across_sources[vllm] from test_consolidator_router_e2e.py  

84 requests failed
assert 84 == 0

ℹ️ Info

No other issues found (see more)

❄️ No new flaky tests detected

🔄 Datadog retried 1 test - 0 passed on retry

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[jthomson04]

Approved. I left two non-blocking follow-up comments inline.