[aw][code health] dead code branch in `_format_log_files_line` — `unreadable < 0` is structurally unreachable

[microsasa]

Root Cause

_format_log_files_line in vscode_report.py has three branches:

unreadable = found - parsed
if unreadable > 0:   # ← reachable: some files failed to parse
    ...
if unreadable < 0:   # ← dead: structurally unreachable
    return (f"... ([yellow]{found} found; inconsistent counts[/yellow])")
return f"[bold]Log Files:[/bold]  {parsed}"

The unreadable < 0 case implies log_files_parsed > log_files_found. This can never be true because get_vscode_summary constructs the accumulator as:

acc = _SummaryAccumulator(log_files_found=len(logs))  # parsed starts at 0
for log_path, file_id in log_ids:
    try:
        ...
    except OSError:
        continue  # parsed NOT incremented on failure
    acc.log_files_parsed += 1  # incremented only on success

log_files_parsed starts at zero and is only incremented on successful reads; it can never exceed log_files_found = len(logs). The unreadable < 0 guard was likely added as a defensive measure when the counts were computed separately, but the invariant parsed ≤ found is now guaranteed by construction.

Impact

The dead branch is harmless but:

1. Misleads future readers into thinking parsed > found is a realistic runtime state.
2. The companion test test_inconsistent_counts_shown_when_parsed_exceeds_found in test_vscode_report.py exercises this impossible state, adding noise to the test suite and coverage numbers without guarding against a real regression.
3. The docstring on _format_log_files_line says "surfacing unreadable or inconsistent counts" — the second clause documents behaviour that can't occur.

Fix

1. vscode_report.py — remove the if unreadable < 0: branch and update the docstring to drop the "inconsistent counts" reference:

   def _format_log_files_line(summary: VSCodeLogSummary) -> str:
       """Build the 'Log Files' line, surfacing unreadable file counts."""
       found = summary.log_files_found
       parsed = summary.log_files_parsed
       unreadable = found - parsed
       if unreadable > 0:
           return (
               f"[bold]Log Files:[/bold]  {parsed}"
               f" ({found} found, "
               f"[red]{unreadable} unreadable[/red])"
           )
       return f"[bold]Log Files:[/bold]  {parsed}"

2. tests/copilot_usage/test_vscode_report.py — remove test_inconsistent_counts_shown_when_parsed_exceeds_found entirely (it tests an impossible state and has no value as a regression guard).

Testing Requirement

After the removal:

• Verify the remaining two test cases (test_unreadable_files_shown_when_found_exceeds_parsed and test_happy_path_no_unreadable_annotation) still pass — they cover the only two real branches.
• make check must pass (lint + typecheck + all tests).
• No new test is needed: the removed branch is unreachable by design.

Warning

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