Kevin Chevalier 5fa2283123 Fix read_files with out-of-bounds line ranges producing empty result (#9326) ...

## Description

Fixes APP-4002

<img width="444" height="303" alt="Screenshot 2026-04-28 at 5 42 20 PM"
src="https://github.com/user-attachments/assets/1c45e5fa-1a20-4aa9-8666-c6d59b781fa5"
/>


This is a defensively coded UI in case something else leads to missing
file contexts.

<img width="469" height="113" alt="Screenshot 2026-04-28 at 5 40 44 PM"
src="https://github.com/user-attachments/assets/f2bd2c03-c529-49a2-8c6c-4d1efdc37544"
/>



When an LLM requests a `read_files` tool call with line ranges entirely
beyond EOF (e.g., lines 1891–2090 of a 1237-line file), the client
returns `ReadFilesResult::Success { files: [] }` — the file silently
vanishes from the result. This renders as an empty box with a green
checkmark in the blocklist UI.

**Root cause:** `TextFileAccumulator::flush_range` only emitted a
segment on final flush for whole-file reads (`final_flush &&
self.whole_file`). For ranged reads where no lines fall within the
requested range, the buffer stays empty and no segment is emitted. The
file ends up in neither `file_contexts` nor `missing_files`.

**Fix:**
1. **Primary:** Change `flush_range` to always emit a segment on final
flush (`!self.buf.is_empty() || final_flush`), so every requested range
produces a `TextFileSegment` even when entirely past EOF.
2. **Defensive:** Add rendering fallback that shows a red X error box
with "Failed to read files" when `ReadFilesResult::Success` has empty
`file_contexts`, preventing empty boxes for any future edge case.
3. **Tests:** Updated existing test and added two new tests covering
out-of-bounds ranges on non-empty files.

## Testing

- Updated `empty_file_with_ranges_produces_no_segment` →
`empty_file_with_ranges_produces_empty_segment` (expects 1 segment with
empty content)
- Added `range_past_eof_produces_empty_segment` — 5-line file, range
10..15
- Added `multiple_ranges_some_past_eof` — 5-line file, ranges [1..3,
10..15]
- All 23 text_file_reader tests pass
- `cargo fmt` and `cargo clippy` clean

## Agent Mode
- [x] Warp Agent Mode - This PR was created via Warp's AI Agent Mode

## Changelog Entries for Stable

CHANGELOG-BUG-FIX: Fixed read_files tool showing an empty box when the
LLM requests line ranges beyond the end of a file.

---


[Conversation](https://staging.warp.dev/conversation/ef9f9688-ca1e-4eb3-b29a-35c5c13e80da)
| [Plan](https://staging.warp.dev/drive/notebook/lAlU2uG6KN5y96mdmk8wYL)

Co-Authored-By: Oz <oz-agent@warp.dev>

Co-authored-by: Oz <oz-agent@warp.dev>

2026-04-30 11:55:25 -05:00

..

src

Fix read_files with out-of-bounds line ranges producing empty result (#9326)

2026-04-30 11:55:25 -05:00

test_data

Initial public release of Warp.

2026-04-28 08:43:33 -05:00

Cargo.toml

Initial public release of Warp.

2026-04-28 08:43:33 -05:00