TUI hangs in infinite render loop after auto-resume abort fails with session ID parse error #29868

Description

OpenCode 1.15.12 hangs in an infinite TUI rendering loop after the auto-resume mechanism fails to abort a stuck subagent. The main thread spins indefinitely in renderer.CliRenderer.prepareRenderFrame -> buffer.OptimizedBuffer.setCellWithAlphaBlendingCell.

Reproduction

Not fully deterministic, but the trigger appears to be:

1. A parent session spawns a subagent that gets stuck
2. Auto-resume triggers abort+resume after ~16s idle
3. The abort hits a session-ID parse error: Expected a string starting with "ses", got "%7Bid%7D"
4. The TUI renderer then enters a tight spin loop (~40% CPU sustained), never recovering

Evidence

Log excerpt (09:53:36)

ERROR service=server ref=err_688474cc error="Expected a string starting with \"ses\", got \"%7Bid%7D\""

%7Bid%7D is URL-encoded {id} — a template literal that was not interpolated before being passed as a session ID.

Stack sample (main thread saturated)

renderer.CliRenderer.prepareRenderFrame
  buffer.OptimizedBuffer.setCellWithAlphaBlendingCell
    buffer.OptimizedBuffer.set

The process stays in S+ state with ~22% CPU for 30+ minutes until killed.

Environment

• OpenCode version: 1.15.12
• Platform: macOS (Darwin)
• Installed via: mise
• Terminal: ttys016