## Summary
- Add `start_line_one_indexed` and `end_line_one_indexed_inclusive`
optional parameters to the `read_file` agent tool, allowing the agent to
read specific line ranges from files
- Update consent preview to display line range (e.g., "Read src/App.tsx
(lines 10-50)") and XML builder to include `start_line`/`end_line`
attributes
- Add comprehensive unit tests (36 tests) with minimal mocking, using
real temp files on disk

## Test plan
- [x] All 36 new unit tests pass covering: schema validation, full file
reads, start-only, end-only, both params, edge cases (out-of-bounds
clamping, start > end, empty files, single-line files), consent preview,
and XML builder
- [x] All 747 existing tests pass (no regressions)
- [x] Lint, formatting, and type checks pass

🤖 Generated with [Claude Code](https://claude.com/claude-code)
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<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Adds optional line range parameters to the read_file tool so the agent
can read specific lines and reflect the range in consent preview and
XML. Improves safety with clamping, schema validation, and clear errors,
backed by comprehensive tests.

- **New Features**
- Support start_line_one_indexed and end_line_one_indexed_inclusive to
read a specific line range.
- Consent preview shows ranges; XML builder adds start_line/end_line
attributes.

- **Bug Fixes**
- Escape start_line/end_line in XML and update parser to accept
dyad-read tags with attributes.
- Validate start <= end and fix trailing newline handling to match
full-file reads.

<sup>Written for commit 4c96f70ff20ba37bee46955b739a693acd0afc0c.
Summary will update on new commits.</sup>

<!-- End of auto-generated description by cubic. -->

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Medium Risk**
> Expands an agent file-access primitive and changes how `<dyad-read>`
tags are parsed, which could affect context gathering and partial reads;
behavior is well-covered by new unit tests but still touches
security-adjacent tooling.
> 
> **Overview**
> Adds optional `start_line_one_indexed` /
`end_line_one_indexed_inclusive` parameters to the local agent
`read_file` tool so it can return a specific line range (with bounds
clamping and trailing-newline preservation).
> 
> Updates consent previews and `<dyad-read>` XML generation to
surface/encode the requested range, and loosens
`parseFilesFromMessage`’s `<dyad-read>` regex to tolerate extra
attributes. Includes a comprehensive new `read_file` unit test suite
covering schema validation, range behavior, and XML/preview formatting.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
4c96f70ff20ba37bee46955b739a693acd0afc0c. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

---------
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>