[Bug] Subagent spawning fails with xhigh/max reasoning due to prompt length limits

Bug Description
when using xhigh or max, unable to spawn subagents because of prompt hit length limits:
⏺ Explore(Find auto-save client code)
Done (0 tool uses · 0 tokens · 1s)

⏺ Explore(Find server auto-save handlers)
Done (0 tool uses · 0 tokens · 1s)

⏺ Explore(Find Sentry config + scrubbing)
Done (0 tool uses · 0 tokens · 1s)

Subagent prompts hit length limits. Investigating directly.

Environment Info

• Platform: darwin
• Terminal: ghostty
• Version: 2.1.126
• Feedback ID: 01a092a7-3dcc-4567-a901-f55711e45104

Errors

[{"error":"Error: NON-FATAL: Lock acquisition failed for /Users/pz/.local/share/claude/versions/2.1.126 (expected in multi-process scenarios)\n    at r86 (/$bunfs/root/src/entrypoints/cli.js:2768:2177)\n    at HD8 (/$bunfs/root/src/entrypoints/cli.js:2768:1257)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-04T18:55:15.252Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"prompt is too long: 213350 tokens > 200000 maximum\"},\"request_id\":\"req_011Cai3T9vQmUgHA5Kf7Jgi1\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:57327)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:50:4943)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-04T18:59:33.796Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"prompt is too long: 213350 tokens > 200000 maximum\"},\"request_id\":\"req_011Cai3TxgG6i4uPJigd97K1\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:57327)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:50:4943)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-04T18:59:45.199Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"prompt is too long: 213350 tokens > 200000 maximum\"},\"request_id\":\"req_011Cai3UZ3Ut91sdDsf11NQB\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:57327)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:50:4943)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-04T18:59:53.050Z"}]