[MODEL] Opus 4.6/4.7 gives error when starting session with SKILL /session-start
Status Fixed / completed
Reported on v2.1.112
Maintainer reply None cached
Activity 4 comments · opened Apr 16, 2026 · closed Apr 17, 2026
Preflight Checklist
- [x] I have searched existing issues for similar behavior reports
- [x] This report does NOT contain sensitive information (API keys, passwords, etc.)
Type of Behavior Issue
Claude refused a reasonable request
What You Asked Claude to Do
I start and end a session with a SKILL: /session-start & /session-end
With Opus 4.6 or 4.7 this gives an error the last day.
The error does not occur when I switch to Sonnet.
What Claude Actually Did
Claude gave me an error:
⎿ API Error: Extra usage is required for 1M context · run /extra-usage to enable, or /model to switch to standard context
This is strange as the is only around 18KB loaded.
Expected Behavior
Claude should have: executed these SKILLS
Files Affected
No files affected.Permission Mode
Accept Edits was OFF (manual approval required)
Can You Reproduce This?
Yes, every time with the same prompt
Steps to Reproduce
/session-start of /session-end give same error.
Claude Model
Opus
Relevant Conversation
⎿ API Error: Extra usage is required for 1M context · run /extra-usage to enable, or /model to switch to standard contextImpact
Medium - Extra work to undo changes
Claude Code Version
2.1.112
Platform
Anthropic API
Additional Context
I have a Claude Max subscription and did not reach my limit yet.
4 Comments
Found 3 possible duplicate issues:
This issue will be automatically closed as a duplicate in 3 days.
🤖 Generated with Claude Code
Running
/sessie-startunder an Opus session throws an API error. Same patternlikely affects any skill that hard-pins a different model than the host session.
## Root cause
The skill's YAML frontmatter hard-pinned
model: sonnet:```yaml
---
name: sessie-start
disable-model-invocation: true
model: sonnet
---
When the host conversation runs on Opus, Claude Code attempts to switch the
skill's execution to Sonnet mid-session. Under certain conditions (possibly
related to the 1M-context extra-usage state on Opus 4.7, CC 2.1.112) this
cross-model switch fails with an API error, blocking the skill from running.
Fix
Change model: sonnet to model: inherit so the skill runs on whatever model
the host session uses:
---
name: sessie-start
disable-model-invocation: true
model: inherit
---
Verified: /sessie-start now runs cleanly under Opus.
### Fix
Two valid patterns, depending on the skill's needs:
1. Mechanical skills (orchestration, file I/O, dashboard calls) — run on
Sonnet in an isolated subagent:
```yaml
---
name: session-start
disable-model-invocation: true
context: fork
model: sonnet
agent: general-purpose
---
The context: fork + agent: <type> combination creates an isolated subagent
where the model switch is safe. The skill loses access to the host conversation
context, so it must pull everything it needs via bash calls, file reads, or
dynamic context injection (!
command).A bare model: override without context: fork triggers the cross-model switch error.
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