feat(skills): add e2e browser and CLI/TUI driving recipes

skills/agentic-end-to-end-testing/driving-cli-tui.md

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+# Driving a CLI / TUI (tmux)
+
+Each scenario gets its own named tmux session (cleanup needs a deterministic
+name). Fix the size for deterministic capture; prefer the app's plain-text/inline
+mode if it has one.
+
+## The four-command recipe
+
+```bash
+tmux new-session -d -s <name> -x 200 -y 50 "<cmd> 2>/tmp/<name>-stderr.log"
+tmux send-keys -t <name> -l "literal text"   # -l = no key-name parsing (paths, slashes)
+tmux send-keys -t <name> Enter
+tmux capture-pane -t <name> -p                # -p = plain text; add -e only for styling
+```
+
+- `-x 200 -y 50` fixes the pane size so `capture-pane` output is deterministic
+  run to run — a resized pane reflows text differently.
+- Always `-l` for user-typed strings; without it a literal path like
+  `/foo/bar` gets parsed as arrow-key escapes instead of typed characters.
+- Redirect stderr to a file — panics, log lines, and debug probes land there,
+  not in the pane, so they won't show up in a `capture-pane` snapshot at all.
+
+Kill any leftover session with the same name before starting a new one, so
+reruns don't attach to a stale process:
+
+```bash
+tmux kill-session -t <name> 2>/dev/null   # idempotent: fine if nothing to kill
+```
+
+## Form fill: send-keys patterns
+
+`send-keys` parses keystrokes by name (`Enter`, `BTab`, `C-u`) unless you pass
+`-l` for literal text. A typical field-by-field fill mixes both:
+
+```bash
+tmux send-keys -t <name> BTab                 # shift-tab to a prior field
+tmux send-keys -t <name> C-u                  # clear the current line
+tmux send-keys -t <name> -l "some/literal/path"   # literal — no key parsing
+tmux send-keys -t <name> Tab                  # forward to the next field
+tmux send-keys -t <name> Enter
+```
+
+`sleep 0.3` between keys is usually enough; bump to 0.5–1.0s for field
+transitions where the UI re-renders.
+
+## Polling capture-pane for state
+
+Poll `capture-pane -p` for a state string and grep the **glyph or word**, not
+the color — `-p` drops ANSI styling by default (add `-e` only if you need
+styling), and colors are also just harder to grep reliably than a fixed
+glyph:
+
+```bash
+for i in $(seq 1 30); do
+  pane=$(tmux capture-pane -t <name> -p)
+  echo "$pane" | grep -q "state: processing" && break
+  sleep 1
+done
+```
+
+TUIs commonly use a distinct glyph per state, e.g. a Braille spinner (`⠋`)
+while pending and an X mark (`✗`) on failure, with the glyph simply removed
+once reconciled. Grep for the glyph itself, not for a color code.
+
+## Two captures for optimistic UI
+
+Mirror the web sync/async pattern: capture the pane immediately after the
+triggering keypress, then again after a reconcile window. Without the
+immediate capture you can't tell "rendered then reconciled" from "never
+rendered":
+
+```bash
+tmux send-keys -t <name> -l "trigger the optimistic action"
+tmux send-keys -t <name> Enter
+echo "=== synchronous ===" ; tmux capture-pane -t <name> -p | grep -E "pending-glyph"
+sleep 6
+echo "=== reconciled  ===" ; tmux capture-pane -t <name> -p | grep -E "pending-glyph" || echo "[no pending — reconciled]"
+```
+
+## Plain-text mode over the alt-screen buffer
+
+If the TUI has a flag that disables its alternate-screen buffer (a debug or
+plain-output mode), use it when launching under tmux. `capture-pane` then sees
+plain scrollback text instead of raw escape sequences from a full-screen
+redraw, which is much easier to grep.
+
+## Non-interactive CLIs don't need tmux
+
+If the surface under test is a one-shot command rather than an interactive
+session, skip tmux entirely — run the command and capture its stdout/stderr
+directly. The tmux machinery exists for interaction, not for driving a binary
+in general. Still run it against a real, freshly built instance, not a stale
+one left over from an earlier session.