Re-add code block formatting instructions (#29574)

Richard Feldman created

Re-enabled instructions about code block formatting.

In practice, the model doesn't seem to use these very often, but there's
no negative effect on evals. In a future PR, I'll experiment with adding
more evals around the model actually using the code blocks.

2 runs before: (`--repetitions=8`)
```
=================================================================
                            AGGREGATE
=================================================================


4 examples failed to run!
Average programmatic score: 37%
Average diff score: 66%
Average thread score: 93%


-----------------------------------------------------------------
                     CUMULATIVE TOOL METRICS
-----------------------------------------------------------------

β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
β”‚             Tool             β”‚   Uses   β”‚ Failures β”‚   Rate   β”‚
β”œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€
β”‚edit_file                     β”‚   398    β”‚    53    β”‚   13%    β”‚
β”‚terminal                      β”‚    11    β”‚    1     β”‚    9%    β”‚
β”‚create_file                   β”‚    40    β”‚    2     β”‚    5%    β”‚
β”‚read_file                     β”‚   245    β”‚    8     β”‚    3%    β”‚
β”‚find_path                     β”‚    48    β”‚    0     β”‚    0%    β”‚
β”‚list_directory                β”‚    13    β”‚    0     β”‚    0%    β”‚
β”‚grep                          β”‚   133    β”‚    0     β”‚    0%    β”‚
β”‚thinking                      β”‚    18    β”‚    0     β”‚    0%    β”‚
β”‚diagnostics                   β”‚   130    β”‚    0     β”‚    0%    β”‚
```

```
=================================================================
                            AGGREGATE
=================================================================


1 examples failed to run!
Average programmatic score: 41%
Average diff score: 68%
Average thread score: 96%


-----------------------------------------------------------------
                     CUMULATIVE TOOL METRICS
-----------------------------------------------------------------

β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
β”‚             Tool             β”‚   Uses   β”‚ Failures β”‚   Rate   β”‚
β”œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€
β”‚fetch                         β”‚    1     β”‚    1     β”‚   100%   β”‚
β”‚edit_file                     β”‚   553    β”‚    63    β”‚   11%    β”‚
β”‚read_file                     β”‚   349    β”‚    3     β”‚    1%    β”‚
β”‚diagnostics                   β”‚   158    β”‚    0     β”‚    0%    β”‚
β”‚find_path                     β”‚    70    β”‚    0     β”‚    0%    β”‚
β”‚list_directory                β”‚    10    β”‚    0     β”‚    0%    β”‚
β”‚thinking                      β”‚    45    β”‚    0     β”‚    0%    β”‚
β”‚grep                          β”‚   213    β”‚    0     β”‚    0%    β”‚
β”‚create_file                   β”‚    24    β”‚    0     β”‚    0%    β”‚
β”‚terminal                      β”‚    17    β”‚    0     β”‚    0%    β”‚
β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜
```

1 run after this change:

```
=================================================================
                            AGGREGATE
=================================================================

Average programmatic score: 42%
Average diff score: 74%
Average thread score: 100%


-----------------------------------------------------------------
                     CUMULATIVE TOOL METRICS
-----------------------------------------------------------------

β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
β”‚             Tool             β”‚   Uses   β”‚ Failures β”‚   Rate   β”‚
β”œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€
β”‚edit_file                     β”‚   534    β”‚    92    β”‚   17%    β”‚
β”‚read_file                     β”‚   325    β”‚    6     β”‚    2%    β”‚
β”‚list_directory                β”‚    6     β”‚    0     β”‚    0%    β”‚
β”‚thinking                      β”‚    12    β”‚    0     β”‚    0%    β”‚
β”‚create_file                   β”‚    16    β”‚    0     β”‚    0%    β”‚
β”‚diagnostics                   β”‚    49    β”‚    0     β”‚    0%    β”‚
β”‚grep                          β”‚   234    β”‚    0     β”‚    0%    β”‚
β”‚find_path                     β”‚    65    β”‚    0     β”‚    0%    β”‚
β”‚terminal                      β”‚    38    β”‚    0     β”‚    0%    β”‚
β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜
```


Release Notes:

- N/A

Change summary

assets/prompts/assistant_system_prompt.hbs | 14 ++++++++++++++
1 file changed, 14 insertions(+)

Detailed changes

assets/prompts/assistant_system_prompt.hbs πŸ”—

@@ -36,6 +36,20 @@ If appropriate, use tool calls to explore the current project, which contains th
 - The user might specify a partial file path. If you don't know the full path, use `find_path` (not `grep`) before you read the file.
 {{/if}}
 
+## Code Block Formatting
+
+Whenever you mention a code block, you MUST use ONLY use the following format when the code in the block comes from a file
+in the project:
+
+```path/to/Something.blah#L123-456
+(code goes here)
+```
+
+The `#L123-456` means the line number range 123 through 456, and the path/to/Something.blah
+is a path in the project. (If this code block does not come from a file in the project, then you may instead use
+the normal markdown style of three backticks followed by language name. However, you MUST use this format if
+the code in the block comes from a file in the project.)
+
 ## Fixing Diagnostics
 
 1. Make 1-2 attempts at fixing diagnostics, then defer to the user.