[Bug] Subagent dispatch fails with "Extra usage required for 1M context" on Max plan despite included feature

Bug Description
[Subject] Subagent + WebSearch fail on Max plan with "Extra usage is required for 1M context" —
regression

Environment

• Claude Code: 2.1.123 (macOS, Apple Silicon)
• Plan: Max ($200/mo)
• Model: claude-opus-4-7 (Opus 4.7, 1M context)
• Effort level: xhigh
• Extra-usage toggle: NOT enabled (intentionally — 1M is supposed to be included on Max)

Symptom
Every Task-tool subagent dispatch (in our case manager-tdd and expert-backend) returns within
~1s with:
API Error: Extra usage is required for 1M context · run /extra-usage to enable, or /model to
switch to standard context
The same error blocks WebSearch from subagent contexts. The parent session itself is fine — only
delegated agents fail.

Expected
Per the March 13, 2026 announcement and the in-app docs, 1M context on Opus 4.6 / 4.7 is INCLUDED
in Max plan with no extra-usage toggle required. Subagents should inherit the parent's plan
coverage, not require a separate per-call extra-usage check.

Actual

• 100% failure rate on subagent dispatch.
• Failure happens before the agent's first tool call — the prompt is rejected at request time.
• Parent session continues to work, including direct WebSearch from parent.

Repro

1. Max plan, Opus 4.7 selected via /model. 2. Ensure /extra-usage is OFF.
2. From a fresh session, dispatch any subagent. 4. Observe immediate error.

Cross-references
Already-filed issues with the same root cause: #44117, #45390, #46780, #46967. #44117 is the
closest match. All still affect 2.1.123. Please consider this a +1 with the additional data point
that 2.1.123 does not fix the regression.

Impact
SPEC-driven workflows that rely on subagent delegation are completely blocked on Max plan despite
1M being a paid feature. Users either downgrade context or pay extra-usage on top of Max
(double-billing).

Request
Treat as a regression. Propagate the parent session's "1M is included on Max" flag to spawned
subagent requests so they don't trip the per-call extra-usage gate.

Environment Info

• Platform: darwin
• Terminal: tmux
• Version: 2.1.123
• Feedback ID: fa9b09df-f5f8-4062-ac70-f4481cbc65ad

Errors

[{"error":"Error: NON-FATAL: Lock acquisition failed for /Users/goos/.local/share/claude/versions/2.1.123 (expected in multi-process scenarios)\n    at x86 (/$bunfs/root/src/entrypoints/cli.js:2769:2177)\n    at Jw8 (/$bunfs/root/src/entrypoints/cli.js:2769:1257)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-30T08:56:33.027Z"},{"error":"Error: Request was aborted.\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:50:3448)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-30T08:56:41.297Z"}]