```                   # 📋 Session Report
    λλ              
   λ⊙λ⊙             
  λλλλλλ            
 λλλλλλλλ           
    λλ              
    λλ              
    λλ              
    λλ              
    λλ              
    λλ              
    λλ              
    λλ              
```                 

**🔑 Session ID:** 17a8c39a-e877-42a5-be01-d7610396f90d

---

## 📊 Statistics

### Turn Counts

| Metric | Value |
|--------|-------|
| Total Turns | 26 |
| 👤 User Turns | 13 |
| 🤖 LLM Turns | 13 |

### 🔧 Tool Calls

**Total Tool Calls:** 12

`bash_write-file     `    5 ████████████████████████████████████████████████████████████

`bash_check-code     `    4 ████████████████████████████████████████████████

`bash_read-file      `    2 ████████████████████████

`bash_list-files     `    1 ████████████


### 💾 Byte Usage

`Input     `      1 MiB ████████████████████████████████████████████████████████████

`Output    `      3 KiB 

`Reasoning `     27 KiB 
**Total:** 2 MiB


### 🎫 Token Usage

`Prompt      `  1,341,006 ████████████████████████████████████████████████████████████

`Completion  `     36,814 ███

`Cached      `  1,300,025 ████████████████████████████████████████████████████
**Total:** 1,702,810

_(1,300,025 cached)_


### 📡 Signal Metrics

**Informativeness Score:** 100/100 🟢

#### Interaction Signals

| Signal | Status | Details |
|--------|--------|---------|
| Misalignment | ⚠️ 5 | 5 instances detected

#### Execution Signals

| Signal | Status | Details |
|--------|--------|---------|
| Failures | ⚠️ 11 | 11 tool/action failures

#### Environment Signals

| Signal | Status | Details |
|--------|--------|---------|
| Exhaustion | ⚠️ 13 | 13 resource boundary hits: timeout, connection_error, service_unavailable, internal_error
---

## 👤 Step 1: User Turn

### 📝 System Prompt

```
You are an expert Haskell and Bash programmer specialized in writing clean, idiomatic, and efficient Haskell code.
When writing Bash code:
- Avoid bash-specific logic but bash-ism are fine.
- Document required shell tools at the top of the bash script.
When writing Haskell code:
- Use modern Haskell practices (base >= 4.14)
- Prefer pure functions and explicit type signatures
- Use standard libraries when appropriate
- Add clear comments for complex logic
- Follow consistent formatting
Use list-files to explore the project structure, read-file to understand existing code, write-file to create or modify files, and check-code to verify your work.
Always compile code before considering the job done.
Your output format may be stored as commit message: hence the first line of your last message should be a summary line.
You have access to a tool which is a copy of yourself named io_prompt_agent_oneshot, use it when a task is well-scoped in a way that it would save tokens in your context window and not interfere with your work.
```

### 💬 User Query

# Fix write-file-range: indentation stripping and verify off-by-one line handling

Depends-on: 
Base-branch: main
Final: false

## Problem 1: Indentation Stripping Bug (CONFIRMED)

The `write-file-range` capability in `executeWriteFileRange` strips indentation from replacement content.

### Location
- File: `src/System/Agents/Tools/DeveloperToolbox.hs`
- Function: `executeWriteFileRange` (around line 420)

### Current buggy code
```haskell
let contentBlocks = map Text.strip $ Text.splitOn "---" contentTxt
```

The `Text.strip` call removes leading and trailing whitespace from each content block, which destroys indentation in code files.

### Impact
If you try to replace a range with indented content like:
```haskell
    let x = 1
        y = 2
    in x + y
```

It becomes:
```haskell
let x = 1
    y = 2
in x + y
```

The leading indentation is stripped, corrupting the code.

### Fix
```haskell
-- Change from:
let contentBlocks = map Text.strip $ Text.splitOn "---" contentTxt

-- To:
let contentBlocks = Text.splitOn "---" contentTxt
```

---

## Problem 2: Off-by-One Line Number Handling (NEEDS VERIFICATION)

There may be an off-by-one error in how line numbers are interpreted when replacing/deleting ranges.

### Reported Behavior
When instructed to delete range 366, it appears to affect line 365 instead.

### Expected Behavior
Line numbers should be 1-based and inclusive:
- Range "5" should replace/delete line 5 only
- Range "3-5" should replace/delete lines 3, 4, and 5

### Current Implementation
In `applyRangeReplacement`:
```haskell
Lines (start, end) ->
    let totalLines = length originalLines
        actualStart = max 1 start
        actualEnd = min end totalLines
     in if actualStart > actualEnd || actualStart > length currentLines
            then currentLines
            else
                let before = take (actualStart - 1) currentLines  -- lines before start
                    after = drop actualEnd currentLines             -- lines after end
                 in before ++ newLines ++ after
```

This looks correct on paper:
- `actualStart - 1` converts 1-based to 0-based index for `take`
- `drop actualEnd` correctly drops 0-based indices 0 to (end-1), keeping from index `end` onwards

### Verification Needed
The logic appears correct, but the reported issue suggests there may be:
1. A subtle off-by-one somewhere else in the processing
2. An edge case with certain file formats
3. Confusion about what line number is being targeted

**This needs investigation with targeted tests.**

---

## Required Tests

Add tests to `test/DeveloperToolboxTests.hs` to verify fixes:

### Test 1: Indentation Preservation
```haskell
testIndentationPreservation :: Assertion
testIndentationPreservation = withTempDir $ \tmpDir ->
    withStandardTestFile tmpDir $ \filePath -> do
        toolbox <- testToolbox
        let indentedContent = "    let x = 1\n        y = 2\n    in x + y\n"
        result <- DeveloperToolbox.executeWriteFileRange silent toolbox filePath "3" indentedContent
        case result of
            Left err -> assertFailure $ show err
            Right _ -> do
                content <- Text.readFile filePath
                assertBool "Should preserve 4-space indentation" $
                    "    let x = 1" `Text.isInfixOf` content
                assertBool "Should preserve 8-space indentation" $
                    "        y = 2" `Text.isInfixOf` content
```

### Test 2: Single Line Deletion Verification
```haskell
testSingleLineDeletion :: Assertion
testSingleLineDeletion = withTempDir $ \tmpDir ->
    withStandardTestFile tmpDir $ \filePath -> do
        toolbox <- testToolbox
        -- Create a file with numbered lines for precise verification
        let numberedContent = Text.unlines $ map (\n -> "Line " <> Text.pack (show n)) [1..10]
        Text.writeFile filePath numberedContent
        
        -- Delete line 5
        result <- DeveloperToolbox.executeWriteFileRange silent toolbox filePath "5" ""
        case result of
            Left err -> assertFailure $ show err
            Right _ -> do
                content <- Text.readFile filePath
                let lines' = Text.lines content
                -- After deleting line 5, what was line 6 should now be at position 5
                assertBool "Line 5 should be removed (no 'Line 5' in output)" $
                    not ("Line 5" `Text.isInfixOf` content)
                assertBool "Line 4 should still be present" $
                    "Line 4" `Text.isInfixOf` content
                assertBool "Line 6 should still be present (now at position 5)" $
                    "Line 6" `Text.isInfixOf` content
                length lines' @?= 9  -- Should have 9 lines after deletion
```

### Test 3: Edge Case - First Line
```haskell
testReplaceFirstLine :: Assertion
testReplaceFirstLine = withTempDir $ \tmpDir ->
    withStandardTestFile tmpDir $ \filePath -> do
        toolbox <- testToolbox
        result <- DeveloperToolbox.executeWriteFileRange silent toolbox filePath "1" "NEW FIRST LINE\n"
        case result of
            Left err -> assertFailure $ show err
            Right _ -> do
                content <- Text.readFile filePath
                let lines' = Text.lines content
                head lines' @?= "NEW FIRST LINE"
```

### Test 4: Multi-Range with Indented Content
```haskell
testMultiRangeIndentation :: Assertion
testMultiRangeIndentation = withTempDir $ \tmpDir ->
    withStandardTestFile tmpDir $ \filePath -> do
        toolbox <- testToolbox
        let block1 = "    block1 line1\n    block1 line2\n"
        let block2 = "        block2 line1\n        block2 line2\n"
        let content = block1 <> "---" <> block2
        result <- DeveloperToolbox.executeWriteFileRange silent toolbox filePath "2,8" content
        case result of
            Left err -> assertFailure $ show err
            Right _ -> do
                fileContent <- Text.readFile filePath
                assertBool "First block indentation preserved" $
                    "    block1 line1" `Text.isInfixOf` fileContent
                assertBool "Second block indentation preserved" $
                    "        block2 line1" `Text.isInfixOf` fileContent
```

---

## Trade-offs and Considerations

### For Problem 1 (Indentation):
- **Proposed Fix**: Remove `Text.strip` entirely
- **Consideration**: Users will need to be careful about trailing newlines in their content blocks
- **Alternative**: Could strip only trailing whitespace/newlines but preserve leading indentation

### For Problem 2 (Off-by-one):
- The current code looks correct but needs testing to confirm
- May need to audit all places where line numbers are converted between 1-based (user) and 0-based (internal)

---

## Acceptance Criteria

- [ ] Indentation stripping bug is fixed
- [ ] Tests confirm indentation is preserved across single and multi-range operations
- [ ] Tests confirm line numbers are correctly interpreted (1-based, inclusive)
- [ ] All existing tests continue to pass
- [ ] Edge cases (first line, last line, empty ranges) are covered by tests

---
From #529



### 🛠️ Available Tools

- **bash_grep-files** (`bash_grep-files`)
  - Description: Search for a pattern in files using 'git grep'
- **bash_read-file** (`bash_read-file`)
  - Description: Read the contents of a file
- **bash_check-code** (`bash_check-code`)
  - Description: Check Haskell code by compiling or testing
- **bash_list-files** (`bash_list-files`)
  - Description: List all files in the project
- **bash_write-file** (`bash_write-file`)
  - Description: Write content to a file. Optionally compiles or tests the code after writing. Use 'none' for the check action when making multiple edits that are not yet final, to avoid redundant compilation.
- **bash_run_agents_exe** (`bash_run_agents_exe`)
  - Description: Runs agents-exe with specified arguments. Useful for testing CLI commands like init, check, run, describe, and running repro cases when bug with specific command arise.
- **io_prompt_agent_oneshot** (`io_prompt_agent_oneshot`)
  - Description: asks a prompt to the expert agent: oneshot
- **io_prompt_agent_faq** (`io_prompt_agent_faq`)
  - Description: asks a prompt to the expert agent: faq

---

## 🤖 Step 2: LLM Turn

### 💭 Thinking Process

<details>
<summary>Click to expand reasoning</summary>

The user wants me to fix a bug in the `write-file-range` capability. Let me start by exploring the project structure and understanding the codebase.

The main issues are:
1. Indentation stripping bug - `Text.strip` is being used which removes leading whitespace
2. Potential off-by-one line number handling issue that needs verification

Let me start by exploring the project structure and reading the relevant files.
</details>

### 💬 Response

I'll start by exploring the project structure and reading the relevant files to understand the codebase.

### 🔧 Tool Calls

- **bash_list-files**

---

## 👤 Step 3: User Turn



---

## 🤖 Step 4: LLM Turn

### 💭 Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Now let me read the DeveloperToolbox.hs file to understand the current implementation of `executeWriteFileRange` and `applyRangeReplacement`.
</details>

### 💬 Response



### 🔧 Tool Calls

- **bash_read-file**

---

## 👤 Step 5: User Turn



---

## 🤖 Step 6: LLM Turn

### 💭 Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Now let me look at the test file to understand the current test structure and how to add new tests.
</details>

### 💬 Response

Now let me read the test file to understand the current test structure:

### 🔧 Tool Calls

- **bash_read-file**

---

## 👤 Step 7: User Turn



---

## 🤖 Step 8: LLM Turn

### 💭 Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Now I understand the codebase. Let me fix the bugs:

1. **Indentation Stripping Bug**: In `executeWriteFileRange`, the line:
   ```haskell
   let contentBlocks = map Text.strip $ Text.splitOn "---" contentTxt
   ```
   needs to be changed to:
   ```haskell
   let contentBlocks = Text.splitOn "---" contentTxt
   ```

2. **Add tests** for:
   - Indentation preservation
   - Single line deletion verification
   - Replace first line
   - Multi-range with indented content

Let me also verify the line number handling. Looking at `applyRangeReplacement`:

```haskell
Lines (start, end) ->
    let totalLines = length originalLines
        actualStart = max 1 start
        actualEnd = min end totalLines
     in if actualStart > actualEnd || actualStart > length currentLines
            then currentLines
            else
                let before = take (actualStart - 1) currentLines  -- lines before start
                    after = drop actualEnd currentLines             -- lines after end
                 in before ++ newLines ++ after
```

This looks correct to me:
- `take (actualStart - 1)` takes lines 0 to (start-2), which are all lines before the start line
- `drop actualEnd` drops lines 0 to (end-1), keeping lines from index `end` onwards

But wait, I see the problem! `drop actualEnd` should be correct because:
- For range "5" (Lines (5,5)):
  - actualStart = 5, actualEnd = 5
  - before = take 4 currentLines (lines 0-3, i.e., file lines 1-4)
  - after = drop 5 currentLines (drops file lines 1-5, keeps from file line 6 onwards)

The logic seems correct. Let me verify with a concrete example. Say we have file lines [1,2,3,4,5,6,7,8,9,10] and we want to replace line 5:
- originalLines = ["1","2","3","4","5","6","7","8","9","10"]
- start=5, end=5
- actualStart=5, actualEnd=5
- before = take 4 currentLines = ["1","2","3","4"]
- after = drop 5 currentLines = ["6","7","8","9","10"]
- result = ["1","2","3","4"] ++ newLines ++ ["6","7","8","9","10"]

This correctly replaces line 5. The logic appears sound, but the reported issue suggests otherwise. I'll implement the tests to investigate further and confirm whether the bug exists in practice.
</details>

### 💬 Response

Now I understand the codebase. Let me:

1. Fix the indentation stripping bug by removing `Text.strip` from the content block splitting
2. Add comprehensive tests for indentation preservation and line number handling

Let me first fix the bug:

### 🔧 Tool Calls

- **bash_write-file**

---

## 👤 Step 9: User Turn



---

## 🤖 Step 10: LLM Turn

### 💭 Thinking Process

<details>
<summary>Click to expand reasoning</summary>

The code compiles. Now let me add the new tests for indentation preservation and line number handling. I'll update the test file to add the new tests.
</details>

### 💬 Response

The fix compiles. Now let me add the comprehensive tests for indentation preservation and line number handling:

### 🔧 Tool Calls

- **bash_write-file**

---

## 👤 Step 11: User Turn



---

## 🤖 Step 12: LLM Turn

### 💭 Thinking Process

<details>
<summary>Click to expand reasoning</summary>

The code compiles. Now let's run the tests to make sure everything works correctly.
</details>

### 💬 Response

The code compiles. Now let's run the tests to verify everything works:

### 🔧 Tool Calls

- **bash_check-code**

---

## 👤 Step 13: User Turn



---

## 🤖 Step 14: LLM Turn

### 💭 Thinking Process

<details>
<summary>Click to expand reasoning</summary>

We have some test failures. The tests revealed some issues with the test assertions themselves, not with the actual fix. Let me analyze the failures:

1. `Single line deletion (line 5)`: expected 10 lines but got 9. This is actually correct - we deleted line 5, so we should have 9 lines, not 10. The test assertion is wrong.

2. `Replace last line`: The issue is with the test logic. Let me check the test again.

3. `Range deletion at boundaries`: Similar issue with the test.

4. `Sequential line replacement`: The test needs fixing.

The issue is that `Text.lines` strips the trailing newline, so a 10-line file with a trailing newline produces 10 lines, but when we write with `Text.unlines`, it adds a trailing newline. Let me fix the tests.

Let me update the tests to fix these issues. The indentation preservation tests passed, which confirms the fix is working correctly.
</details>

### 💬 Response

I see the tests revealed some issues with the test assertions. The indentation preservation tests all passed, which confirms the fix is working correctly. Let me fix the failing line number handling tests:

### 🔧 Tool Calls

- **bash_write-file**

---

## 👤 Step 15: User Turn



---

## 🤖 Step 16: LLM Turn

### 💭 Thinking Process

<details>
<summary>Click to expand reasoning</summary>

The code compiles. Now let's run the tests again to make sure everything passes.
</details>

### 💬 Response



### 🔧 Tool Calls

- **bash_check-code**

---

## 👤 Step 17: User Turn



---

## 🤖 Step 18: LLM Turn

### 💭 Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Almost there! Just one test failing: "Range deletion at boundaries". The issue is that after the first deletion (lines 1-2), the file is modified, but the second part of the test tries to delete lines 7-8, which should work correctly. Let me look at the test logic more carefully.

Actually, the test reuses the same file for both deletions. After deleting lines 1-2, the file now contains lines 3-10 (as "Line 3", "Line 4", etc.), and we're trying to delete lines 7-8, which would be the 7th and 8th lines of the remaining file, which would be "Line 9" and "Line 10" in the original numbering.

But the test is checking for "Line 7" and "Line 8" in the content, which no longer exist because they're now "Line 3" through "Line 10" after the first deletion.

The test logic is flawed because it checks for "Line 7" and "Line 8" when after the first deletion, those lines are no longer in the file. The remaining lines are "Line 3", "Line 4", "Line 5", "Line 6", "Line 7", "Line 8", "Line 9", "Line 10".

So lines 7-8 in the current file would be "Line 9" and "Line 10" from the original file. Let me fix this test.

Actually, I need to reconsider the test. The second deletion targets lines 7-8 in the modified file. After the first deletion:
- Original lines: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
- After deleting 1-2: 3, 4, 5, 6, 7, 8, 9, 10 (8 lines total)

The second deletion is for lines 7-8, which would be the last two lines: "Line 9" and "Line 10" from the original file. The test assertion should verify that "Line 9" and "Line 10" are gone after the second deletion. The remaining lines should be 3, 4, 5, 6, 7, 8 (original lines).
 
I see the discrepancy now. The test is failing because it expects "Line 7" and "Line 8" to be present, but after two deletions, the file's line numbering has changed. The original "Line 7" and "Line 8" are still in the file, but their positions have shifted. This means the test's expectations don't align with the actual file content after the second deletion. I'll need to adjust the test to correctly track which lines should remain and which should be removed after multiple deletions.
</details>

### 💬 Response

Almost there! Just one test failing. Let me fix the range deletion test - the issue is that the assertions need to account for the cumulative effect of both deletions:

### 🔧 Tool Calls

- **bash_write-file**

---

## 👤 Step 19: User Turn



---

## 🤖 Step 20: LLM Turn

### 💭 Thinking Process

<details>
<summary>Click to expand reasoning</summary>

The code compiles. Now let's run the tests again to make sure everything passes.
</details>

### 💬 Response



### 🔧 Tool Calls

- **bash_check-code**

---

## 👤 Step 21: User Turn



---

## 🤖 Step 22: LLM Turn

### 💭 Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Still one test failing. The issue is with the "Range deletion at boundaries" test. Let me trace through what's happening:

1. File created with "Line 1" through "Line 10"
2. First deletion: lines 1-2 are deleted. The file should now have: Line 3, Line 4, Line 5, Line 6, Line 7, Line 8, Line 9, Line 10 (8 lines)
3. Second deletion: lines 7-8 of the current file are deleted. These would be "Line 9" and "Line 10" from the original

The assertion "Line 1 should be removed" is failing. This suggests that the file content still contains "Line 1" after the first deletion. Let me debug this.

Wait, looking at the code more carefully, the issue might be that after the first write, the file has new content, but "Line 1" might still appear in a different form. Or the contentBlocks with `Text.strip` removal might not be working as expected...

Wait, I already removed `Text.strip` in the fix. Let me look at the test more carefully. 

Oh wait, the test output says "Line 1 should be removed". But `Text.isInfixOf` is checking if "Line 1" appears anywhere in the content. If we delete lines 1-2, we should have lines 3-10 remaining. The content should contain "Line 3", "Line 4", etc., but NOT "Line 1".

Let me trace through what happens with `applyRangeReplacement`:
- Original lines: ["Line 1", "Line 2", "Line 3", ..., "Line 10"]
- Delete lines 1-2 (start=1, end=2)
- actualStart = max 1 1 = 1
- actualEnd = min 2 10 = 2
- before = take (1-1) currentLines = take 0 ["Line 1", ...] = []


- after = drop 2 ["Line 1", "Line 2", "Line 3", ...] = ["Line 3", "Line 4", ...]
- result = [] ++ [] ++ ["Line 3", ...] = ["Line 3", ...]

I'm noticing something peculiar about the `contentBlocks` when an empty string is passed. When we split an empty string by "---", it returns [""], a list with a single empty string. This might be causing unexpected behavior in the replacement process. The empty block could potentially interfere with the expected line deletion mechanism, leaving traces of the original content that should have been removed.

The check for `length contentBlocks /= length ranges` seems to have a subtle interaction with single-range operations. When there's only one range, this validation might not catch edge cases involving empty content blocks. The logic allows the operation to proceed even with an empty content block, which could explain why the test is seeing unexpected results.

The bottom-to-top application of range replacements appears to be functioning correctly, with the sorted pairs ensuring proper ordering. However, something in the content block handling seems to be preventing complete line removal.

I'm particularly interested in how the code handles empty content blocks for single-range scenarios, and whether there's a specific edge case being triggered in this test scenario.

The filtering mechanism for removing empty strings from lines might be introducing unexpected behavior during the test validation process. This could potentially mask or alter the expected line manipulation outcome.

The test's focus on verifying the correct lines remain after targeted deletion suggests a nuanced interaction between the replacement logic and content validation checks.

The code's handling of empty content blocks and line splitting seems to have specific edge cases that could be causing unexpected behavior, particularly when filtering lines and performing range-based replacements.

I suspect the `Text.isInfixOf` check might be failing due to how newlines are being processed or preserved during the file manipulation. The test output's lack of detailed information makes precise debugging challenging, indicating I need to add more explicit diagnostic checks to understand exactly where the comparison is breaking down.

The range logic appears sound on the surface - converting start and end lines to 0-based indices and then reconstructing the file with `unlines` - but something subtle is happening with line preservation or deletion that's not immediately obvious.

I'm noticing a potential issue with the empty string replacement, where the line splitting and rejoining might not behave as expected, especially when handling an empty content block.

The test failure suggests that "Line 1" remains in the file after attempted deletion, which points to a potential problem with how the range replacement handles boundary conditions. I need to trace through how the file content is being manipulated to understand why the expected line removal isn't occurring.

The code block handling for single ranges looks suspicious, particularly how empty content blocks are processed and compared against the specified ranges. Something in the logic for splitting and reassembling the file content seems to be preventing the complete removal of the targeted lines.

The code is deliberately structured to avoid stripping whitespace from content blocks, which means trailing newlines will be preserved exactly as they exist in the input text. This could explain why the replacement isn't working as expected when an empty string is passed.

When an empty replacement string is provided, the resulting content block becomes `[]`, effectively deleting the lines within the specified range. The code path handles empty content blocks by converting them to a list containing an empty string, ensuring range matching works correctly even with single-range scenarios.

The implementation carefully tracks range modifications and ensures that empty content blocks trigger line removal while maintaining the original file structure.

The splitting logic reveals an interesting edge case: when splitting an empty string, the result is a list with one empty element, which could potentially impact line replacement behavior.

This subtle interaction between content splitting and replacement might explain the test failure, suggesting a nuanced problem with how empty content blocks are processed during file modifications.

The line conversion process seems particularly sensitive, with `Text.lines` on an empty string producing an empty list, and `Text.unlines` potentially introducing unexpected newline characters during file writing.

I'll trace the `unlines` behavior, noting that an empty list returns an empty string, but a list with empty strings creates newline characters. This could trigger subtle file format changes during sequential line replacements.

The investigation points toward a potential newline handling issue, where repeated file modifications might inadvertently alter the file's structural composition.

The `Text.isInfixOf` check suggests something unexpected is happening with line preservation. I'm curious whether the replacement operation is truly removing the specified line or if some internal logic is preventing the expected deletion.

I need to verify the exact mechanics of how the replacement content is being processed and applied, particularly when an empty string is passed as the replacement.

The code path reveals an interesting pattern: the implementation seems designed to handle multiple ranges, with specific logic for single versus multi-range scenarios that might be influencing the replacement behavior.

When processing a single range with an empty content block, the code falls into a specific branch that replaces lines differently from multi-range scenarios. This suggests there could be a subtle edge case in how empty content blocks are handled during line replacement.

The code checks if content blocks are empty and provides a default empty string, which then gets processed through `Text.lines`, potentially creating unexpected behavior when no actual content is provided.

The current implementation means an empty replacement effectively deletes the specified line range, but the interaction between single and multi-range logic might reveal an interesting implementation detail.

The output string construction looks particularly nuanced, with potential implications for how line endings are handled when the original file contains or lacks trailing newlines.

I suspect the key issue involves how `Text.unlines` processes an empty list and whether this triggers unexpected file formatting. The conditional logic around `hasTrailingNewline` seems critical to understanding the potential text manipulation edge case.

The test case is checking for the presence of "Line 1" after deletion, with a specific assertion that this line should be removed. This suggests we need to carefully examine how file content is being reconstructed after line range deletion.

I'll investigate the `applyRangeReplacement` function to understand the precise mechanism of line removal and text reconstruction, focusing on how empty lines and newline characters are managed during this process.

The range specification `Lines (1, 2)` targeting lines 1 and 2 indicates an attempt to remove specific content, which means our implementation must precisely handle partial file modifications while preserving the remaining line structure.

The key observation is how the function handles partial line ranges, ensuring that non-targeted lines remain intact during the replacement process.

By calculating `actualStart` and `actualEnd` within the existing line range, the function safely extracts pre-range and post-range content segments. This allows precise surgical modification of text without disrupting the overall file structure.

The `before` and `after` line collections are strategically constructed using `take` and `drop` operations, enabling a clean reconstruction of the file with the new content seamlessly integrated.

The pattern matching ensures that only valid, non-overlapping ranges trigger the replacement mechanism, with a fallback to preserve the original lines if the range criteria aren't met.

The code handles head and tail appends through simple list concatenation, while more complex line range replacements involve carefully calculated index manipulations. The core logic involves extracting specific line segments and reconstructing the content with new material inserted at the precise location.

When processing multi-range replacements, a subtle nuance emerges in how empty content blocks interact with the replacement strategy. The code carefully checks whether multiple content blocks exist, defaulting to an empty string if no specific replacement content is provided. This approach ensures flexibility in handling different replacement scenarios while maintaining the structural integrity of the original text.

The sorting mechanism for range-content pairs introduces an additional layer of complexity, using a descending order based on the range's starting position. This suggests a deliberate strategy to process replacements from bottom to top, potentially preventing index shifting complications during sequential modifications.

The key observation centers on the bottom-to-top replacement strategy, which seems designed to preserve line number references throughout the multi-range transformation process.

The specific test case involving lines 1-2 reveals a potential edge case in this approach. When replacing from the file's beginning, the standard "bottom-to-top" logic encounters an interesting scenario where the first range processed is actually the topmost range, which could introduce subtle complexities in line tracking and replacement.

The `foldl` implementation with `applyRangeReplacement` suggests an intriguing interaction between range application and line number preservation, especially when dealing with ranges near the file's start.

By tracing through the execution with the given example, I see the function first calculates boundaries by taking lines before the start and dropping lines after the end. When replacing lines 1-2 with an empty list, the result effectively removes those lines while preserving the remaining content.

The sorted pairs mechanism ensures replacements occur in a specific order, with this particular range being processed first due to its start position. The final result confirms the lines are successfully removed, leaving only the remaining content intact.

However, the subsequent test check suggests an unexpected behavior. Despite the replacement appearing correct, the file might not reflect the expected changes. This hints at a potential issue with how `Text.unlines` handles newline characters or how the file is being written and read back.

The conversion process reveals a subtle nuance: `Text.lines` removes trailing newlines, while `Text.unlines` always adds one. This could explain why the original file with 10 lines becomes problematic when reconstructed, potentially leaving an extra empty line that interferes with the test's expectations.

The file writing mechanism seems straightforward - `Text.writeFile` should handle the content correctly. Yet something in the line transformation process is causing unexpected results when checking for line removals.

The test environment involves a temporary directory with a numbered text file containing lines from 1 to 10. The current investigation focuses on understanding how line deletions are being processed and verified after the file replacement operation.

The core test logic checks whether specific lines can be removed from the file, with the first test case attempting to delete lines 1-2 and confirming their absence. A previous single-line deletion test passed, suggesting the range deletion mechanism might have some nuanced behavior not immediately apparent.

The key question emerging is whether the issue stems from how multi-line ranges are handled compared to single-line deletions, or if there's a subtle difference in content block processing that affects line preservation.

When an empty content block is provided, the code uses an empty string as a default, which would result in no lines being written for that specific range - effectively deleting those lines. This seems consistent with the expected behavior of removing lines when no replacement content is specified.

The verification steps confirm that after line replacement, specific lines like "Line 1" should no longer exist in the file, while other lines such as "Line 3" should remain intact. The test aims to validate this precise line manipulation mechanism.

Something subtle is happening with the write or read process that prevents the expected line deletion. The multiple delete operations might be introducing unexpected behavior, potentially related to how the second deletion interacts with the first.

I'm considering whether the second file deletion attempt is somehow interfering with the initial line removal, possibly through unexpected file handling or content manipulation mechanisms.

The sequential deletion approach - first removing lines 1-2, then targeting lines 7-8 - suggests a potential complexity in tracking line positions after the first modification. This could reveal a nuanced interaction between consecutive file modification operations that isn't immediately apparent.

The test output indicates a failure specifically around line 1 removal, which points to a potential issue in how the initial deletion is being processed or verified. I need to trace how the file content changes after the first deletion to understand why the assertion is failing.

My next step would be to introduce more granular logging or debug checks to capture the exact file state after each deletion operation, which might illuminate the underlying problem with the line removal mechanism.

The failure in the `testRangeDeletionAtBoundaries` test suggests there might be a subtle interaction between how `unlines` handles empty content and how the file is being rewritten. I suspect the key issue could be related to how empty lines or newline characters are being processed during the file modification sequence.

The `Text.unlines` function always appends a newline, even for an empty list, which means an empty replacement doesn't result in a truly empty file. This subtle behavior might be causing unexpected results when attempting to completely remove specific lines.

I'm tracking how this impacts line deletion, particularly in the first test case where lines are being completely removed. The investigation centers on understanding how the newline preservation and empty content interact during file manipulation.

The output construction logic seems complex, involving conditions about trailing newlines and empty line lists. This suggests the file writing mechanism has nuanced behavior that could affect line removal expectations.

The code's handling of edge cases - like empty files and newline preservation - reveals intricate logic that might explain the test discrepancy. Something subtle is happening in how the file content is being reconstructed and written.

I need to carefully trace the exact sequence of content transformations to understand why the expected file state isn't matching the actual result. The interaction between `unlines`, newline handling, and empty line scenarios appears to be the key investigative path.

The sorting mechanism and bottom-to-top application of ranges might introduce unexpected behaviors, especially when dealing with empty replacement content. This could potentially alter file content in ways not immediately apparent from a surface-level review.

My current hypothesis is that the issue stems from a fundamental misunderstanding in how multi-range operations interact with empty content blocks. The test assertion suggests the implementation is behaving differently than expected when attempting to remove or modify line ranges.

The test name "Range deletion at boundaries" implies a focus on testing deletion scenarios, which means the current implementation might need a more nuanced approach to handling empty or minimal content replacements across multiple line ranges.

Specifically, the single-range scenario with an empty content block triggers a particular code path that differs from multi-range empty block handling. This subtle difference could be the root cause of the unexpected test behavior.

The code's logic for single-range operations seems straightforward: it allows the operation to proceed without validating the content block, effectively treating an empty content block as a valid replacement strategy. This means when a single range is specified, the system will simply replace that range with an empty content block, regardless of whether it's technically \"empty\" or not.

The range application mechanism then processes this empty content block, using it to reconstruct the file's contents by replacing the specified lines with nothing, effectively deleting those lines from the output.

The `applyRangeReplacement` function handles this by splitting the content into lines, which in the case of an empty string, results in an empty list. This allows for precise line-by-line manipulation, where the specified range can be surgically removed or replaced without disrupting the surrounding file structure.

I'm tracing through the range replacement logic, focusing on how lines are selected and reconstructed. The `before` and `after` segments are carefully extracted using `take` and `drop` operations, ensuring that only the intended lines are modified.

The `foldl` application on a single range seems straightforward, and the file writing mechanism with `Text.writeFile` should preserve the transformed content correctly. The test's assertion about line removal appears consistent with the expected behavior.

The current line of investigation centers on understanding why the test perceives a line as not removed when the code suggests it should be. The output construction using `unlines` looks clean, and the newline handling seems appropriate.

I'm scrutinizing the `unlines` documentation, which confirms it preserves existing line endings without adding extra newlines. This means the file writing process should be transparent and predictable. The test's failure might stem from a subtle interaction between `isInfixOf` and the actual file content.

The test logic specifically checks for the absence of "Line 1" after a deletion operation. Something in how the replacement occurs isn't completely eliminating the original line content as expected. I need to trace how the replacement function handles empty or partial line removals.

The `applyRangeReplacement` function seems complex, potentially processing replacement blocks in a specific order that might not match my initial assumptions about how line deletions should work.
</details>

### 💬 Response

Let me look at this more carefully. The test is still failing. Let me check what the actual issue is with the range deletion test. Looking at the code, the test deletes lines 1-2 and then checks if "Line 1" is removed. The problem might be that the test logic is checking for "Line 1" which could also match "Line 10", "Line 11", etc. Let me fix the test to be more precise:

### 🔧 Tool Calls

- **bash_write-file**

---

## 👤 Step 23: User Turn



---

## 🤖 Step 24: LLM Turn

### 💭 Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Let me run the tests now to see if the fix works.
</details>

### 💬 Response



### 🔧 Tool Calls

- **bash_check-code**

---

## 👤 Step 25: User Turn



---

## 🤖 Step 26: LLM Turn

### 💭 Thinking Process

<details>
<summary>Click to expand reasoning</summary>

All 644 tests pass now. Let me summarize what was done:

1. **Fixed the indentation stripping bug** in `executeWriteFileRange`:
   - Changed `let contentBlocks = map Text.strip $ Text.splitOn "---" contentTxt` 
   - To `let contentBlocks = Text.splitOn "---" contentTxt`
   - Added a comment explaining why we don't strip whitespace (to preserve indentation)

2. **Added comprehensive tests** for:
   - Indentation preservation (4 tests covering single line, multi-range, nested indentation, and tab indentation)
   - Line number handling (5 tests covering single line deletion, first line replacement, last line replacement, range deletion at boundaries, and sequential line replacement)

The fix ensures that when using `write-file-range`, the replacement content's indentation is preserved, which is crucial for code files where indentation has semantic meaning.
</details>

### 💬 Response

All 644 tests pass. Let me provide a summary of the changes made:

## Summary of Changes

### Problem 1: Indentation Stripping Bug (FIXED)

**Location:** `src/System/Agents/Tools/DeveloperToolbox.hs`, function `executeWriteFileRange`

**The Fix:**
Changed from:
```haskell
let contentBlocks = map Text.strip $ Text.splitOn "---" contentTxt
```
To:
```haskell
-- NOTE: We do NOT strip whitespace from content blocks to preserve
-- indentation. This is intentional - stripping would corrupt code.
let contentBlocks = Text.splitOn "---" contentTxt
```

This preserves leading whitespace (indentation) in replacement content, which is essential for code files where indentation has semantic meaning.

### Problem 2: Line Number Verification

The existing code was already handling 1-based line numbers correctly. The investigation confirmed:
- Range "5" correctly replaces/deletes line 5 only
- Range "3-5" correctly replaces/deletes lines 3, 4, and 5
- The logic `take (actualStart - 1)` and `drop actualEnd` correctly converts 1-based to 0-based indexing

### Tests Added

Added comprehensive tests to `test/DeveloperToolboxTests.hs`:

**Indentation Preservation Tests (4 tests):**
1. `testIndentationPreservation` - Single line replacement with Haskell-style indentation
2. `testMultiRangeIndentation` - Multi-range operations preserve different indentation levels
3. `testNestedIndentation` - Python-style nested indentation (4, 8, 12 spaces)
4. `testTabIndentation` - Tab characters are preserved

**Line Number Handling Tests (5 tests):**
1. `testSingleLineDeletion` - Verify deleting line 5 removes exactly that line
2. `testReplaceFirstLine` - Verify line 1 can be replaced correctly
3. `testReplaceLastLine` - Verify last line (line 10) can be replaced
4. `testRangeDeletionAtBoundaries` - Verify range deletions at start/end of file
5. `testSequentialLineReplacement` - Verify multi-range replacements work correctly

All 644 tests pass, confirming the fix works correctly and doesn't break existing functionality.
