edit is now the primary editing method, yet its output was a dry one-line
status ("Edited …: replaced X B with Y B") while edit_lines/smart_edit showed a
highlighted unified diff. Carry the unified diff in ToolResult.metadata["diff"]
(kept out of the model-facing output, so the agent's context is unchanged) and
render it in the TUI: dim summary line plus highlighted diff (green +, red -,
dim @@). Falls back to plain text when no diff metadata is present.

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

Previously the action and primary path were crammed into the title
("→ filesystem read src/main.py") and the body only held the extra args,
so for simple actions (info/delete/mkdir/exists) the card body was empty.

Title is now compact ("→ filesystem <action>"). The body always carries
the information: "path: <path>" (accent) leads, "destination: <dest>"
(accent) follows for move/copy/diff, then the per-action args (range/
content/old+new/operations/instruction/pattern/question …) as before.
The card is never empty.

Tests updated: title carries action only (path is in the body),
destination lands in the body for move/copy/diff, info shows path in body,
path value is styled accent. 42 filesystem-renderer tests total. Full
suite 827 passed, 1 skipped.

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

The generic ToolStartedRenderer dumped all of args as JSON, so filesystem
cards showed "→ filesystem" with no action in the title and the full
content/old/new text for write/edit/smart_edit flooding the card.

New FilesystemToolStartedRenderer (clients/terminal/tui/renderers/filesystem.py):
- Title carries the action and primary path: "→ filesystem read src/main.py";
  move/copy/diff also append "→ <destination>".
- Body is a compact per-action summary instead of JSON:
  - read: range (offset–limit) + numbered flag
  - write/append: content preview (first line + "(+N lines)" hint, not full)
  - edit: old + new previews
  - edit_lines: operations count + op kinds (replace/delete/insert, first 5)
  - smart_edit: instruction preview
  - grep: pattern + glob + regex flag
  - find/find_up: pattern
  - query: question preview
  - list: recursive flag
  - info/delete/mkdir/exists: empty body (path is in the title)
- Body keys render dim, values in text.
- Sub-agent cards indented, matching ToolStartedRenderer.

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

13 new tests cover accepts, title (action/path/destination), empty body for
info, and per-action body summaries (read/write/edit/edit_lines/grep/
smart_edit/query), content preview truncation, subagent indent, and body key
styling. 42 filesystem-renderer tests total. Full suite 827 passed, 1 skipped.

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

find: the "[N matches for 'pattern' in path ⠠ …]" header plaque is dim
(warning color on ⠠ truncated); "No matches for …" renders dim; each match
line "{path}  ({size})" renders the path in text, "  (" and the size in
dim, and the "<dir>" marker in info.

find_up: a resolved path renders in accent; "not found (searched: …)"
renders dim.

Fallback narrowed to write/edit/append/move/copy/delete/mkdir/exists/
query/unknown. 5 new tests (find header/matches/truncated/no-matches,
find_up found/not-found); 29 filesystem-renderer tests total. Full suite
814 passed, 1 skipped.

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

read: the "[path  |  N lines  |  size]" header plaque is now dim with the
path highlighted in accent (offset/limit plaque "… lines A–B of N …"
likewise); the "⚠ Large file …" warning line renders in warning color; the
file body renders in text (was dim — readable now) with no syntax
highlighting (rejected by design); numbered reads dim the line numbers and
render line content in text. read errors (not_found, file_too_large) render
in tool_error.

info: each "key:     value" line highlights the key (incl. colon) in accent,
the alignment padding in dim, and the value in text.

Fallback narrowed to write/edit/append/move/copy/delete/mkdir/exists/find/
find_up/query/unknown (statuses and find/query intentionally untouched).
Diff/list/grep from stage 1 unchanged.

6 new tests (read plaque/offset/warn/numbered/error, info keys+values);
24 filesystem-renderer tests total. Full suite 809 passed, 1 skipped.

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>