1. cli/update.ts: Block the update command for third-party providers.
The update mechanism downloads from Anthropic's GCS bucket, which
would silently replace the OpenClaude build (with the OpenAI shim)
with the upstream Claude Code binary (without it). Now shows an
actionable message directing users to rebuild from source.
2. codexShim.ts: Filter thinking blocks from assistant history, matching
the openaiShim behavior. Without this, thinking blocks were included
as plain text in assistant messages for the Codex transport but
excluded for the OpenAI transport — causing inconsistent history
when switching providers mid-session.
Squash the current repository state back into one baseline commit while
preserving the README reframing and repository contents.
Constraint: User explicitly requested a single squashed commit with subject "asdf"
Confidence: high
Scope-risk: broad
Reversibility: clean
Directive: This commit intentionally rewrites published history; coordinate before future force-pushes
Tested: git status clean; local history rewritten to one commit; force-pushed main to origin and instructkr
Not-tested: Fresh clone verification after push
