workflows right pane silently truncates agent list when phase has more than 5 agents

Bug

In the workflows progress view, the right pane consistently shows fewer agents than the left pane counter reports. Based on two reproductions the right pane appears to be a sliding window of the most recent ~9 agents rather than a full list -- oldest completed agents silently drop off the top as new ones arrive.

Steps to reproduce

1. Run any multi-agent workflow where a phase dispatches more than ~9 agents total.
2. Open the workflows progress view and watch a phase with many agents.
3. Left pane count and right pane visible entries diverge as agents accumulate.

Evidence

Example 1 -- Plan phase:
Left pane: Plan 7/7. Right pane shows 5 agents. Missing: cycle-state and plan-commit-c1 (both completed early in the phase).

Example 2 -- Develop phase:
Left pane: Develop 11/12. Right pane shows 9 agents. Missing: the first ready-streaks call and doer-c1-i0-cheap (both completed earliest in the phase). The agents visible are the most recent 9, confirming a sliding-window behaviour.

Visible in Example 2:

• ready-streaks (2nd occurrence)
• doer-c1-i0-standard
• reviewer-c1-i1
• log-append-iter-c1-i1
• ready-streaks (3rd occurrence)
• doer-c1-i1-cheap
• reviewer-c1-i2
• log-append-iter-c1-i2
• doer-c1-i2-standard (in progress)

Expected behaviour

All completed agents in a phase are listed. If the list is too long to display, a scroll or "+N earlier" indicator should be shown. The count in the left pane and the number of visible entries should match.

Actual behaviour

The right pane silently drops the oldest completed agents as new ones arrive, with no indicator that entries are missing. The left pane count correctly reflects all agents; the right pane does not.

Environment

• Claude Code desktop app, Windows 11
• Workflow tool (multi-agent orchestration)