bug: Task expansion fails with JSON parsing error when using claude-code provider #133

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opened 2025-10-14 15:43:22 -06:00 by navan · 0 comments

navan commented

2025-10-14 15:43:22 -06:00

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Originally created by @Kl-11 on 9/1/2025

Task expansion fails with JSON parsing error when using claude-code provider

Description

When using the "claude-code" provider in TaskMaster config, the expand_task command fails with a JSON parsing error. The AI model returns markdown-wrapped JSON (```json) instead of raw JSON, causing the parser to fail with "Unexpected token '`'" error. This affects both individual task expansion and bulk expansion operations.

Steps to Reproduce

Use taskmaster with claude code, no additional APIs. Configured via MCP.
Parse a PRD to generate tasks: task-master parse-prd --input=.taskmaster/docs/prd.txt
Try to expand tasks: task-master expand --id=1 --research
Observe JSON parsing error

Expected Behavior

The expand_task command should successfully parse the AI response and add subtasks to the specified task. The AI model should return raw JSON that can be parsed by the JSON.parse() function.

Actual Behavior

The command fails with error:

Error: Failed to parse JSON response object after both simple and advanced attempts: Unexpected token '`', "```json
{
"... is not valid JSON

The AI model using claude-code provider returns JSON wrapped in markdown code blocks instead of raw JSON.

Screenshots or Logs

Error output:

Error: Failed to parse JSON response object after both simple and advanced attempts: Unexpected token '`', "```json
{
"... is not valid JSON
Version: 0.25.1
Name: task-master-ai
Current Tag: master

Environment

Task Master version: 0.25.1
Node.js version: v24.6.0
Operating system: macOS 26.0 (Build 25A5349a)
IDE (if applicable): Claude Code with MCP integration

Additional Context

The issue appears to be specific to the "claude-code" provider, which seems to format responses as markdown code blocks
Approximately 70% of tasks fail to expand (7 out of 10 failed in testing)
This may be related to how the claude-code provider instructs the model to format responses
The error occurs consistently with certain tasks but not others from the same PRD parsing session
Written by claude

*Originally created by @Kl-11 on 9/1/2025* # Task expansion fails with JSON parsing error when using claude-code provider ### Description When using the "claude-code" provider in TaskMaster config, the expand_task command fails with a JSON parsing error. The AI model returns markdown-wrapped JSON (```json) instead of raw JSON, causing the parser to fail with "Unexpected token '`'" error. This affects both individual task expansion and bulk expansion operations. ### Steps to Reproduce 1. Use taskmaster with claude code, no additional APIs. Configured via MCP. 2. Parse a PRD to generate tasks: `task-master parse-prd --input=.taskmaster/docs/prd.txt` 3. Try to expand tasks: `task-master expand --id=1 --research` 4. Observe JSON parsing error ### Expected Behavior The expand_task command should successfully parse the AI response and add subtasks to the specified task. The AI model should return raw JSON that can be parsed by the JSON.parse() function. ### Actual Behavior The command fails with error: ``` Error: Failed to parse JSON response object after both simple and advanced attempts: Unexpected token '`', "```json { "... is not valid JSON ``` The AI model using claude-code provider returns JSON wrapped in markdown code blocks instead of raw JSON. ### Screenshots or Logs Error output: ``` Error: Failed to parse JSON response object after both simple and advanced attempts: Unexpected token '`', "```json { "... is not valid JSON Version: 0.25.1 Name: task-master-ai Current Tag: master ``` ### Environment - Task Master version: 0.25.1 - Node.js version: v24.6.0 - Operating system: macOS 26.0 (Build 25A5349a) - IDE (if applicable): Claude Code with MCP integration ### Additional Context - The issue appears to be specific to the "claude-code" provider, which seems to format responses as markdown code blocks - Approximately 70% of tasks fail to expand (7 out of 10 failed in testing) - This may be related to how the claude-code provider instructs the model to format responses - The error occurs consistently with certain tasks but not others from the same PRD parsing session - Written by claude