[Bug] Unintended text injection corrupting code files during edits

Description:
During a code edit operation, random unrelated text about geometry/parabolas was injected into a TypeScript file. The injected content had no relation to:

• The user's prompt
• The codebase
• The task being performed

Steps to Reproduce:

1. User asked to fix an issue
2. Claude attempted to edit code
3. The Edit tool was called with old_string and new_string parameters
4. Result: Random geometry text was inserted into the file

Injected Content (excerpt):

• A line with a specified midpoint: Infinite lines (rotating around the midpoint).
• A line with a specified footpoint of perpendicular from a specific point...

### Focus on the Parabola:
For a parabola, specific tangent or normal properties...
Theorem: For each point P on π, there exist exactly two lines...

Expected Behavior:
Only the specified new_string content should be written to the file.

Actual Behavior:
Unrelated text was injected, corrupting the source file.

Environment Info

• Platform: darwin
• Terminal: vscode
• Version: 2.0.76
• Feedback ID: 613b7244-5698-4058-9b5c-b838783106c9

Errors

[{"error":"AggregateError\n    at m3A.from (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:43:63985)\n    at VU.<anonymous> (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:57:10016)\n    at VU.emit (node:events:508:28)\n    at VU.emit (node:domain:489:12)\n    at bw1.<computed> (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:56:3432)\n    at ClientRequest.emit (node:events:508:28)\n    at ClientRequest.emit (node:domain:489:12)\n    at emitErrorEvent (node:_http_client:107:11)\n    at TLSSocket.socketErrorListener (node:_http_client:574:5)\n    at TLSSocket.emit (node:events:508:28)\n    at fzA.request (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:59:2130)\n    at processTicksAndRejections (node:internal/process/task_queues:105:5)\n    at runNextTicks (node:internal/process/task_queues:69:3)\n    at listOnTimeout (node:internal/timers:569:9)\n    at process.processTimers (node:internal/timers:543:7)\n    at async UT2 (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:1845:3609)","timestamp":"2026-01-04T08:47:18.103Z"},{"error":"AggregateError\n    at m3A.from (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:43:63985)\n    at VU.<anonymous> (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:57:10016)\n    at VU.emit (node:events:508:28)\n    at VU.emit (node:domain:489:12)\n    at bw1.<computed> (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:56:3432)\n    at ClientRequest.emit (node:events:520:35)\n    at ClientRequest.emit (node:domain:489:12)\n    at emitErrorEvent (node:_http_client:107:11)\n    at TLSSocket.socketErrorListener (node:_http_client:574:5)\n    at TLSSocket.emit (node:events:508:28)\n    at fzA.request (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:59:2130)\n    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)\n    at async L17 (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:2614:9071)\n    at async file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:2614:9964","timestamp":"2026-01-04T08:47:18.105Z"},{"error":"Error: EISDIR: illegal operation on a directory, read\n    at Module.readFileSync (node:fs:440:20)\n    at file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:9:429\n    at oI (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:8:8084)\n    at Object.readFileSync (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:9:404)\n    at zdB (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:4739:22342)\n    at Object.call (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:1027:942)\n    at Au5 (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:2207:17446)","timestamp":"2026-01-04T08:59:38.206Z"},{"error":"Error: Request was aborted.\n    at _0A._createMessage (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:514:3157)\n    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)","timestamp":"2026-01-04T14:57:29.584Z"},{"error":"Error: Request was aborted.\n    at _0A._createMessage (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:514:3157)\n    at processTicksAndRejections (node:internal/process/task_queues:105:5)\n    at runNextTicks (node:internal/process/task_queues:69:3)\n    at process.processTimers (node:internal/timers:540:9)","timestamp":"2026-01-04T14:59:54.279Z"},{"error":"Error: Request was aborted.\n    at _0A._createMessage (file:///Users/yusuf/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:514:3157)\n    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)","timestamp":"2026-01-04T15:00:24.077Z"}]

<img width="673" height="1120" alt="Image" src="https://github.com/user-attachments/assets/1ec90af4-03f2-46f7-b1c6-4ed0bdf80124" />