Replace the }` heuristic in inject.sh with a brace-depth counter:
start at depth=1 after the opening {, increment on {, decrement on },
stop when depth reaches 0. This correctly handles nested if/else blocks,
loops, and structs that close at 4-space indent inside calculateParams.
Also emit a non-zero exit with a descriptive message if EOF is reached
without finding the matching closing brace.
Add test_inject_extraction.sh covering simple bodies, nested if/else,
multi-level nesting, and the EOF-without-match error case.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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