* fix(github-copilot): preserve all reasoning IDs and add gpt-5.3-codex support
The existing guard (8fd15ed0e5) only skipped rewriting reasoning item IDs
when encrypted_content was a non-null string. When gpt-5.3-codex is used
via GitHub Copilot, the model falls through to the forward-compat catch-all
with reasoning:false, so encrypted_content is never requested and arrives
as null — bypassing the guard and causing a rewrite. Copilot validates
reasoning item IDs server-side regardless of whether the client includes
encrypted_content, so the rewritten id triggers the 400 error.
Two changes:
1. connection-bound-ids.ts: skip ALL reasoning items unconditionally.
Reasoning items always reference server-side state bound to their
original ID; rewriting any of them breaks Copilot's lookup.
2. models.ts + index.ts: extend the forward-compat cloning logic to
cover gpt-5.3-codex (adds it to the template-target set and to
CODEX_TEMPLATE_MODEL_IDS so it can also serve as a template source
for gpt-5.4). Adds gpt-5.3-codex to COPILOT_XHIGH_MODEL_IDS for
the thinking profile.
Thanks @InvalidPandaa.
* docs(github-copilot): clarify gpt-5.3-codex is a no-op template for itself
https://claude.ai/code/session_01EAFmq4WyKkiUkVAqRXp4Bm
* fix(github-copilot): remove dead reasoning prefix branch in deriveReplacementId
https://claude.ai/code/session_01EAFmq4WyKkiUkVAqRXp4Bm
* fix(github-copilot): align reasoning id replay tests
* test(plugin-sdk): use cjs sidecar for require fast path
---------
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Peter Steinberger <steipete@gmail.com>
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