claw/docs/superpowers/specs/2026-04-19-g6-host-bridge-callback-semantics-design.md

G6 Host-Bridge Callback Semantics Design

Date: 2026-04-19 Status: Draft Upstream Report: 2026-04-19-g6-host-bridge-execution-semantics-report.md

1. Intent

This design defines the next bounded slice after G6 host-bridge execution semantics.

The target is:

G6 host-bridge callback semantics

2. Why This Slice

The previous semantic slice isolated two seams, but the tighter next pressure is callback-side semantics:

1. invocation semantics are already identified
2. callback completion semantics still determine whether later real execution can be bounded safely

3. Scope Boundary

This design is limited to callback semantics only.

It may include:

1. defining completion states for callback requests
2. defining blocked/error/partial/ok transitions
3. defining how callback semantics constrain later real-sample entry

It must not include:

1. implementing host-runtime directly
2. executing a G6 real sample
3. reopening G7
4. opening G8

4. Target Outcome

The bounded target outcome is one state:

1. one bounded G6 host-bridge callback semantics plan

5. Exit Condition

This design is complete when implementation can be bounded to one plan that:

1. freezes callback semantics only
2. separates completion state logic from transport/runtime implementation
3. emits one bounded follow-up plan