Fix TypeError in LongCatImageEditPipeline truncation warning

[Ricardo-M-L]

What this PR does

LongCatImageEditPipeline._encode_prompt calls len() twice on an int when building its truncation warning message:

https://github.com/huggingface/diffusers/blob/main/src/diffusers/pipelines/longcat_image/pipeline_longcat_image_edit.py#L284-L289

iflen(all_tokens) >self.tokenizer_max_length:
logger.warning(
"Your input was truncated because \`max_sequence_length\` is set to "f" {self.tokenizer_max_length} input token nums : {len(len(all_tokens))}"
)
all_tokens=all_tokens[: self.tokenizer_max_length]

len(all_tokens) already returns an int, so the outer len() raises TypeError: object of type 'int' has no len() — inside the f-string formatting — every time the branch fires.

Why this is a real bug

The warning only executes when len(all_tokens) > self.tokenizer_max_length (default 512). That is the exact scenario the warning is supposed to inform the user about. Instead of informing them, the pipeline crashes with a TypeError during prompt encoding.

Minimal repro:

pipe=LongCatImageEditPipeline.from_pretrained(...)
pipe(prompt="a very long prompt ..."*200, image=image)
# TypeError: object of type 'int' has no len()

The sibling LongCatImagePipeline._encode_prompt has the correct form at line 291 — this is a local typo in the edit pipeline only.

Fix

Drop the extraneous len() call to match the sibling pipeline:

- f" {self.tokenizer_max_length} input token nums : {len(len(all_tokens))}"+ f" {self.tokenizer_max_length} input token nums : {len(all_tokens)}"

Before submitting

• Did you read the contributor guideline?
• Was this discussed/approved via a Github issue or the forum? N/A — single-character typo fix.
• Did you make sure to update the documentation with your changes? N/A.
• Did you write any new necessary tests? N/A — fixes a log-message crash; no behavior change.

Who can review?

@yiyixuxu@sayakpaul

[Ricardo-M-L]

Polite bump on this one — it's a 1-character TypeError fix (`len(len(all_tokens))` would raise `TypeError: object of type 'int' has no len()` the first time the truncation path actually fires). cc @yiyixuxu in case you have a moment.

CI is green, sitting since 2026-04-21. Happy to address any feedback. 🙏

[Ricardo-M-L]

Hi @yiyixuxu@sayakpaul, friendly ping — this is a one-character typo fix (drops a duplicate len() inside an f-string) that turns the existing truncation warning into a TypeError whenever the user actually hits the truncation path in LongCatImageEditPipeline. The sibling LongCatImagePipeline already has the correct form. Happy to address any feedback 🙏

[Ricardo-M-L]

Hi team, just following up on this PR. Happy to make any changes or address feedback if needed. Thanks for considering it!

[Ricardo-M-L]

Hi! Just a friendly ping on this PR. It's been open for a while — would appreciate a review when you get a chance. Thanks for your time!

[Ricardo-M-L]

Friendly ping - this PR has been open for a while. Would appreciate a review when you get a chance. Thanks!

[yiyixuxu]

hi @Ricardo-M-L

I'm closing this per the AI-assisted contribution guidelines: https://huggingface.co/docs/diffusers/main/en/conceptual/contribution#ai-assisted-and-agentic-contributions

We're seeing an increasing volume of contributions and review capacity is currently our bottleneck, so the guidelines ask for maintainer acknowledgment on an issue before a PR is opened — that's what lets us prioritize the bugs users are actually hitting.

Normally we'd leave this as a suggestion and keep working with a contributor on the PR, but the volume here has made that impractical — these have come in faster than we can review them, so I'm closing all of them that's opened bu you rather than reviewing them individually.