fix(app): slash in the subagent breadcrumb and a quieter subagent bar - #59438

Cherry-pick of #59347 from beta (Kit Langton), so the next dev release has it. It applies to dev unchanged.

In a subagent's session, the breadcrumb uses the same slash all the way along, and the bar in place of the composer is now a quiet one-line status instead of a second composer. A subagent session can't take prompts, so its composer slot shows how the run is going (status, time, agent, model) and a way back to the main session. Nothing about parent sessions or the composer itself changes. ≡ƒöì Origin: seen in real use, from a screen capture with feedback ("shouldn't it just be another slash?", "maybe it should be a dimmer colour and not as large, because now it looks like the other thing"). Γ¥î Before 1. The breadcrumb read project / parent Γ¥» subagent: slashes, then a chevron. Γ¥î 2. The bar was a 104px card with the composer's background, rounding and two rows, so it looked like a text box you could type into. Γ¥î Γ£à After 1. The breadcrumb reads project / parent / subagent, with the same 8px either side as the slash after the project. 2. The bar is one 32px line on the timeline's own background: ⠿ Running · 2h 17m · General · OpenCode / Claude Opus 4.6 · High, all in the faint text colour, with Main session ESC at the end. The timeline fades into it as it scrolls underneath. diff - project / parent Γ¥» subagent + project / parent / subagent - [ card: status row ] [ card: icon ┬╖ agent ┬╖ model ┬╖ variant ┬╖ Main session ] (104px, composer look) + icon ┬╖ status ┬╖ time ┬╖ agent ┬╖ model ┬╖ variant ........ Main session ESC (32px, plain line) ≡ƒôè Proof: a subagent that has been running for 2h 17m, with a long title | | Before | After | |---|---|---| | Header | | | | Bar | | | | Whole view | | | Both updated tests fail without the change: the ancestor-path e2e test (finds 1 slash instead of 4) and the subagent bar component test (the bar is still rounded and 104px tall). ### Visual svg <svg xmlns="http://www.w3.org/2000/svg" width="240" height="72" viewBox="0 0 240 72" fill="none"> <style> .card{opacity:0;animation:card 4s ease-in-out infinite} .line{animation:line 4s ease-in-out infinite} .chev{opacity:0;animation:card 4s ease-in-out infinite} .slash{animation:line 4s ease-in-out infinite} @keyframes card{0%,35%{opacity:1}50%,100%{opacity:0}} @keyframes line{0%,35%{opacity:0}50%,100%{opacity:1}} @media (prefers-reduced-motion:reduce){.card,.line,.chev,.slash{animation:none}} </style> <g stroke="currentColor" stroke-linecap="round" stroke-linejoin="round"> <path d="M16 14h28" stroke-width="4" opacity=".45"/> <path d="M54 18l4-8" stroke-width="1.5" opacity=".4"/> <path d="M68 14h36" stroke-width="4" opacity=".45"/> <path class="chev" d="M114 10l3 4-3 4" stroke-width="1.5"/> <path class="slash" d="M114 18l4-8" stroke-width="1.5" opacity=".4"/> <path d="M128 14h64" stroke-width="4" opacity=".9"/> </g> <g class="card"> <rect x="16.5" y="28.5" width="207" height="37" rx="7" stroke="currentColor" stroke-opacity=".3" fill="currentColor" fill-opacity=".06"/> <path d="M26 38h40M38 56h22M70 56h50M182 56h32" stroke="currentColor" stroke-width="3" stroke-linecap="round" opacity=".6"/> </g> <g class="line" stroke="currentColor" stroke-linecap="round" opacity=".4"> <circle cx="22" cy="56" r="2.5" fill="currentColor" stroke="none"/> <path d="M30 56h22M58 56h16M80 56h20M106 56h46M190 56h30" stroke-width="2.5"/> </g> </svg> ≡ƒæÇ Read: subagent-bar.tsx. The bar keeps the timeline's background and a 16px fade on top because the timeline scrolls on underneath the composer area; without them, scrolled text would show through the status line. The breadcrumb's chevron drawing and its right-to-left flip are gone, since nothing else used them. The rest is routine.