fix: fix cot_output parser

[fatelei]

fix issue langgenius/dify#31034

after

Screen.Recording.2026-01-23.at.21.13.49.mov

This PR contains Changes to Non-Plugin

• Documentation
• Other

This PR contains Changes to Non-LLM Models Plugin

• I have Run Comprehensive Tests Relevant to My Changes

This PR contains Changes to LLM Models Plugin

• My Changes Affect Message Flow Handling (System Messages and User→Assistant Turn-Taking)

• My Changes Affect Tool Interaction Flow (Multi-Round Usage and Output Handling, for both Agent App and Agent Node)

• My Changes Affect Multimodal Input Handling (Images, PDFs, Audio, Video, etc.)

• My Changes Affect Multimodal Output Generation (Images, Audio, Video, etc.)

• My Changes Affect Structured Output Format (JSON, XML, etc.)

• My Changes Affect Token Consumption Metrics

• My Changes Affect Other LLM Functionalities (Reasoning Process, Grounding, Prompt Caching, etc.)

• Other Changes (Add New Models, Fix Model Parameters etc.)

Version Control (Any Changes to the Plugin Will Require Bumping the Version)

• I have Bumped Up the Version in Manifest.yaml (Top-Level Version Field, Not in Meta Section)

Dify Plugin SDK Version

• I have Ensured dify_plugin>=0.3.0,<0.6.0 is in requirements.txt (SDK docs)

Environment Verification (If Any Code Changes)

Local Deployment Environment

• Dify Version is: , I have Tested My Changes on Local Deployment Dify with a Clean Environment That Matches the Production Configuration.

SaaS Environment

• I have Tested My Changes on cloud.dify.ai with a Clean Environment That Matches the Production Configuration

[gemini-code-assist]

Summary of Changes

Hello @fatelei, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves a critical parsing error within the cot_output component of the cot_agent plugin, which was causing functionality issues in the previous version. The changes primarily focus on refining the PrefixMatcher class's step method by eliminating redundant state tracking and simplifying character processing. This ensures more robust and accurate interpretation of agent outputs, thereby stabilizing the plugin's core functionality.

Highlights

• Bug Fix: Addresses a reported issue where the cot_output parser was broken in version 0.0.30 of the plugin.
• Version Update: The cot_agent plugin version has been incremented from 0.0.30 to 0.0.31 in manifest.yaml.
• Code Refactoring: Simplified the parsing logic in cot_output_parser.py by removing the last_character variable and associated state management, which streamlines how character deltas are processed.
• Internal Variable Renaming: Renamed internal variables within the PrefixMatcher.step method (e.g., yield_raw_delta to yield_raw_delta_inner) to improve clarity and avoid potential naming conflicts.

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[gemini-code-assist]

Code Review

This pull request aims to fix an issue with the cot_output parser by removing the logic associated with last_character. While the intent to remove this variable is clear from most of the changes, a critical issue remains in PrefixMatcher.step where last_character is still referenced after its declaration was removed. This will cause a SyntaxError and prevent the code from running. I've provided a specific comment with a code suggestion to resolve this issue.

[Kevin9703]

I tried it, but it still doesn't seem to work

[fatelei]

I tried it, but it still doesn't seem to work

use this patch ? code has not merge, plugin has not been updated

[Kevin9703]

I tried it, but it still doesn't seem to work

use this patch ? code has not merge, plugin has not been updated

Yes, I am using this code

[fatelei]

I tried it, but it still doesn't seem to work

use this patch ? code has not merge, plugin has not been updated

Yes, I am using this code

ok， i will dig it

[fatelei]

I tried it, but it still doesn't seem to work

use this patch ? code has not merge, plugin has not been updated

is this expect ?

[Kevin9703]

I tried it, but it still doesn't seem to work

use this patch ? code has not merge, plugin has not been updated

is this expect ?

Yes, expect to call the tool normally

[fatelei]

I tried it, but it still doesn't seem to work

use this patch ? code has not merge, plugin has not been updated

is this expect ?

Yes, expect to call the tool normally

i submit the code later

[fatelei]

I tried it, but it still doesn't seem to work

use this patch ? code has not merge, plugin has not been updated

is this expect ?

Yes, expect to call the tool normally

code has been updated

[amine-y]

Hello @fatelei , thank you for fixing this do you know when this will get merged?