Fix carriage-return logging when the buffer is empty

[medisean]

Fixes #15420.

The log interceptor now checks that the log deque has an entry before trying to replace an unfinished carriage-return line. This preserves progress-line replacement while allowing tqdm to be the first writer after startup.

Tested with:

• python -m pytest -q tests-unit/app_test/logger_test.py — 1 passed
• python -m compileall -q app/logger.py tests-unit/app_test/logger_test.py
• git diff --check

[github-actions]

✅ All contributors have signed the CLA. Thank you! This PR is ready to be merged.
_{Posted by the CLA Assistant Lite bot.}

[medisean]

I have read and agree to the Contributor License Agreement

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 38d2ce10-f954-40b3-993e-b741ef8db57c

📥 Commits

Reviewing files that changed from the base of the PR and between dd79c64 and e5e8b1d.

📒 Files selected for processing (2)

• app/logger.py
• tests-unit/app_test/logger_test.py

📜 Recent review details

🧰 Additional context used

📓 Path-based instructions (5)

**/*

📄 CodeRabbit inference engine (AGENTS.md)

**/*: Keep changes small, direct, and limited to the narrowest necessary code path and smallest number of files.
Prefer practical fixes, minimal dependencies, and existing repository patterns; remove obsolete, dead, unreachable, or unused code.
Preserve existing APIs, node names, model-loading behavior, file layout, and workflow compatibility unless replacement is explicitly intended.
Core ComfyUI must not add outbound internet requests, telemetry, tracking, reporting, remote configuration, or background network activity. User-authorized model downloads are limited to the requested artifact and must exclude telemetry and unrelated metadata.

Files:

• tests-unit/app_test/logger_test.py
• app/logger.py

**/*.py

📄 CodeRabbit inference engine (AGENTS.md)

**/*.py: Keep state and capability flags on the object that owns the behavior. Prefer explicit parent-owned attributes over probing child objects with getattr; use child checks only when the child owns the delegated behavior.
Preserve shared method signatures, argument order, return shapes, side effects, and error behavior unless every affected caller and interface is intentionally updated.
Do not add unused compatibility parameters, flags, attributes, constructor options, or model-specific options to shared helpers; keep one-off behavior at the integration boundary.
Normalize third-party return conventions at integration boundaries so core code receives the expected type and shape; avoid undocumented caller-side unwrapping.
Do not add torch.no_grad, torch.inference_mode, or inference-mode wrappers. Do not add model freeze/unfreeze toggles; only disable globally enabled inference mode when a training path requires gradients.
Remove inference-only training behavior such as dropout while preserving checkpoint and state-dict compatibility; use nn.Identity when deleting a module would alter keys or ordering.
Keep imports at module scope except established optional-backend probes or imports required to avoid cycles; avoid unnecessary try/except blocks and use specific exceptions with useful fallbacks.
Do not add workarounds for unsupported library versions, especially PyTorch exception-and-float-cast retries, unless a comment names the exact versions still requiring them.
Let unsupported model formats, invalid quantization metadata, and bad states fail with clear errors instead of silently degrading output.
Match local style, keep comments sparse and useful, and remove comments that merely restate obvious code.
Treat dtype, device placement, VRAM use, and offloading as correctness concerns across CPU, CUDA, ROCm, MPS, DirectML, XPU, NPU, and low-VRAM environments.
Prefer existing ComfyUI and Comfy Kitchen operations, quantization helpers, cast/offload helpe...

Files:

• tests-unit/app_test/logger_test.py
• app/logger.py

**/*.{py,json}

📄 CodeRabbit inference engine (AGENTS.md)

Treat legacy combo, io.Combo, and io.DynamicCombo values affecting filesystem access as untrusted; revalidate them at load/save boundaries with folder_paths, containment checks, or fixed allowlists.

Files:

• tests-unit/app_test/logger_test.py
• app/logger.py

**/*.{py,md,txt,json}

📄 CodeRabbit inference engine (AGENTS.md)

Keep warning and info messages short and actionable, remove noisy or misleading logging, and make documentation edits concise, factual, and tied to changed behavior.

Files:

• tests-unit/app_test/logger_test.py
• app/logger.py

**

⚙️ CodeRabbit configuration file

**: IMPORTANT: Only comment on issues directly introduced by this PR's code changes.
Treat AGENTS.md as mandatory repository policy, not optional style guidance.
Flag PR changes that violate AGENTS.md even when the code is otherwise functional.
In particular, enforce architecture boundaries, dtype/device/memory rules,
interface contracts, import style, no unnecessary try/except blocks, no inline
imports, no outbound internet paths in core ComfyUI, and narrow scoped fixes.
Prefer direct findings over suggestions when a rule is violated. Only ignore
AGENTS.md when it clearly conflicts with a newer explicit maintainer instruction
in the PR.
Do NOT flag pre-existing issues in code that was merely moved, re-indented,
de-indented, or reformatted without logic changes. If code appears in the diff
only due to whitespace or structural reformatting (e.g., removing a with: block),
treat it as unchanged. Contributors should not feel obligated to address
pre-existing issues outside the scope of their contribution.

Files:

• tests-unit/app_test/logger_test.py
• app/logger.py

🧠 Learnings (1)

📚 Learning: 2026-02-21T14:01:41.482Z

Learnt from: pythongosssss
Repo: Comfy-Org/ComfyUI PR: 12555
File: comfy_extras/nodes_glsl.py:719-724
Timestamp: 2026-02-21T14:01:41.482Z
Learning: In PyOpenGL, bare Python scalars can be accepted for 1-element array parameters by NumberHandler. This means you can pass an int/float directly to OpenGL texture deletion (e.g., glDeleteTextures(tex)) without wrapping in a list. Verify function-specific expectations and ensure types match what the OpenGL call expects; use explicit lists only when the API requires an array.

Applied to files:

• tests-unit/app_test/logger_test.py
• app/logger.py

🔇 Additional comments (2)

app/logger.py (1)

67-67: LGTM!

tests-unit/app_test/logger_test.py (1)

1-15: LGTM!

---

📝 Walkthrough

Walkthrough

LogInterceptor.write now checks carriage-return progress output only for string data. A unit test verifies that "\rprogress" as the first write creates one log entry with the expected message.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the carriage-return logging fix for an empty buffer.
Description check	✅ Passed	The description explains the logging fix, linked issue, regression test, and validation checks.
Linked Issues check	✅ Passed	The change safely handles the empty log deque and preserves carriage-return replacement behavior with a focused regression test.
Out of Scope Changes check	✅ Passed	The code and test changes are limited to the linked issue's carriage-return logging fix.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}