refactor(cli): throw tool error instead of returning and matching error strings

[uinstinct]

Description

Earlier, the cli used to match for tool errors and cancellations by searching those words in the tool call result. This approach produced errors when the tool call was successful but contained the "error" and "cancelled" words. This PR fixes it.

• removes string matching for error and cancel
• throws errors inside the tool call itself
• update searchCode, writeFile, readFile, listFiles, fetch tools to throw errors instead of returning strings

resolves CON-3796

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Checklist

• [] I've read the contributing guide
• [] The relevant docs, if any, have been updated or created
• [] The relevant tests, if any, have been updated or created

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Summary by cubic

Refactored CLI tool error handling to throw structured errors and propagate execution status, replacing fragile string matching. This prevents false cancellations/errored states and ensures accurate tool result statuses in the UI.

• Bug Fixes

  • Removed string matching for "error" and "cancelled"; use explicit ToolStatus from execution.
  • Permission denials produce canceled entries; execution failures produce errored entries; successful runs are done.

• Refactors

  • Tools now throw ContinueError/Error instead of returning error strings (searchCode, readFile, listFiles, writeFile, fetch, status).
  • Added ToolResultWithStatus and updated executeStreamedToolCalls and handleToolCalls to pass status through chat history.

[cubic-dev-ai]

3 issues found across 9 files

Prompt for AI agents (all 3 issues)

Understand the root cause of the following 3 issues and fix them.


<file name="extensions/cli/src/tools/searchCode.ts">

<violation number="1" location="extensions/cli/src/tools/searchCode.ts:104">
Treating ripgrep exit code 1 as a thrown error regresses the tool: it now fails whenever a search has no matches, whereas ripgrep uses that code to signal an empty result set. Please continue returning the &quot;No matches found&quot; message so successful searches without hits don’t show up as tool errors.</violation>
</file>

<file name="extensions/cli/src/tools/writeFile.ts">

<violation number="1" location="extensions/cli/src/tools/writeFile.ts:165">
Wrapping the caught error in a new Error discards ContinueError reasons and errno metadata, so upstream tool handling always sees an unknown failure reason.</violation>
</file>

<file name="extensions/cli/src/tools/readFile.ts">

<violation number="1" location="extensions/cli/src/tools/readFile.ts:55">
Use ContinueErrorReason.FileNotFound when the target file is missing so downstream tooling can recognize the specific &quot;file not found&quot; condition instead of an unspecified error.</violation>
</file>

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