#23034 Agent chat: no blinking dots before Thinking or Working for; the Steering caption's words are gone

Leo asked for two chat-transcript removals ("wtf have we removed this yet").

1. The blinking dots before "Thinking" / "Working for". Leo called these "the blinking ascii": the three accent dots (WorkingMark) that pulsed on a 2 s cycle at the start of the running turn's line (r2/206.png: "••• Thinking"). The line now starts with its words, and the ticking time shows the turn is alive. The activity line under a todo list (Debug agent.sessionStatus) loses the same dots. WorkingMark.tsx and its CSS are deleted.

2. "Steering · The agent reads it when its current step ends". The caption itself stopped drawing in #22616. Its two strings (steer.waiting, steer.waitingDetail) were still in the catalog, unused, so this PR deletes them and no row can draw them again. A waiting steer shows only the quiet clock and Send now. The "Steered · the agent read it" word-mark is replaced by a ✓ read receipt in #22773 (message-actions lane). This PR doesn't touch SteerMark, so the two PRs don't conflict.

Not changed: the jump-to-latest button's dots. They belong to a different control and are not on the transcript line.

Proof

• webviews/test/transcript-working-line.test.tsx: Thinking, Working for, the call in flight and the activity line each start with their words. The stylesheet has no working-mark or activity-dot rules.
• webviews/test/steer-no-caption.test.tsx: a waiting steer reads only "Send now", and the caption's words are gone from the catalog.
• webviews/test/static-status-loops.test.ts: the fixture drops the two removed loops.
• Gallery: agent-pane.transcript variants thinking and working-tokens play a check that the line has no mark before its words and no looping animation.

Changelog

• Removed: the blinking dots before "Thinking" and "Working for" in agent chat, and the leftover "Steering" caption strings.

Observed / Not run

• Independent review subagent: pass (no correctness findings; nits on stale comments and an over-broad test check, fixed in 578c29c).
• scripts/web-lint.sh: clean on the changed files (the one formatting red is base's test/tool-label-several-files.test.ts, from #23011). prepush-gate.py: no new violations.
• Not run locally: bun tests and gallery plays (no tests on this Mac); CI's react-apps-check and the gallery run cover them.
• cmux-next guards / defaults-snapshot is red on base (stale settings exports for agents.trust.*, sidebar.sessionTree, NotificationModes/Preferences), not from this PR.

Agent session: cosmic-gray

🤖 Generated with Claude Code

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Summary by cubic

Removes the pulsing dots before “Thinking,” “Working for,” and the activity line, so each status starts with its words. Waiting steers no longer show the “Steering” caption; they show only the quiet clock and “Send now.”

• Deletes the unused caption strings from the localization catalog.
• Adds tests and gallery checks for the dot-free status lines and waiting steer.