Standard for diff and read output: the line number (and the +/- marker for
diffs) is the coloured anchor; the content itself reads plainly.

diff: "{num} {marker}  {content}" with num+marker in the marker colour
(green/red), content neutral. Fixed the number-column regex to "^( +)(\d+)|"
so files with more than 9 lines (width > 1) still match — the old
single-space pattern silently fell back to whole-line colouring.
read: "{num}: {content}" with the number in the accent colour, content
neutral (was dim number).

Applied to both clients: the TUI diff/filesystem renderers and the webclient
ToolCard (renderDiff / renderRead). The model-facing text from the server is
unchanged — this is display-only.

_number_diff parses @@ hunk headers and prefixes each content line with its
real file line number: removed/context lines use the old (from) number,
added lines use the new (to) number, in `{marker} {num}│ {content}` form
(marker first so existing startswith highlighting stays valid; column
right-aligned to the largest line number). Hunk/file headers and the
`\ No newline` marker are left unchanged.

Applied in _unified_diff (covers edit / edit_lines / smart_edit) and the
`diff` action — a single server-side change, so both the TUI and the web
client receive numbered diffs in the tool result text.

TUI highlight_unified_diff renders the `{marker} {num}│` column dim and the
content in the marker color, so the number reads as meta, not as part of the
added/removed text. Lines without the prefix (standalone `diff` event, older
callers) are still colored whole.

Co-Authored-By: Claude <noreply@anthropic.com>

The TUI rendered every tool result as a single dim Text in a Panel — no
special handling for filesystem, so unified diffs from edit_lines/smart_edit/
diff were shown as plain grey text (the existing DiffRenderer only fires on
type:"diff", which filesystem never emits), directory listings were an
unaligned text blob, and grep matches had no pattern highlighting.

New FilesystemToolResultRenderer (clients/terminal/tui/renderers/filesystem.py)
intercepts filesystem tool_call events by tool=="filesystem" + args.action:

- diff / edit_lines / smart_edit: reuse a shared highlight_unified_diff()
  helper (extracted from DiffRenderer) — + green, - red, @@ dim; the
  "Applied …" summary line of edit_lines/smart_edit is separated from the
  diff body via a Group; "Files are identical." renders dim.
- list: header plaque dim (warning color on ⚠ truncated); directories
  shown as "▸ name/ (n items)" in info color; files as name (text) +
  size (accent) + time (dim), preserving the tool's fixed-width alignment;
  "?" entries in warning; "(empty directory)" dim.
- grep: header plaque dim; "rel:line:" location dim; matched pattern
  occurrences highlighted in accent (case-insensitive, re.escape'd);
  "No matches …" dim.
- read / info / write / edit / append / move / copy / delete / mkdir /
  exists / find / find_up / query / unknown: plain dim fallback (unchanged
  for now — stage 2). Errors (success=False): plain in tool_error color.

Registered before the generic ToolResultRenderer (first-match wins). The
filesystem tool, WS protocol, events, and webclient are untouched.

22 new tests in tests/clients/test_filesystem_renderer.py cover accepts,
diff/edit_lines/identical/error, list (dir/file/truncated), grep
(pattern/no-matches/no-pattern-arg), fallback, title+status, subagent
indent. DiffRenderer behavior unchanged (existing test still passes).

Co-Authored-By: Claude <noreply@anthropic.com>

- @ file references with glob/dir support and size limits
- ! shell commands with timeout and output truncation
- inline permission dialog for destructive tool calls
- diff and artifact renderers with theme-aware highlighting

Tests: 40 client tests passing