- Relocated compaction, branch-summarization, pruning, and utils from coding-agent to packages/agent/src/compaction.
- Moved OpenAI remote compaction helpers from packages/ai to the new compaction module.
- Added handoff.ts with extractHandoffDocument, createHandoffContext, and renderHandoffPrompt helpers.
- Exposed new entries.ts with standalone SessionEntry types so coding-agent no longer owns them.
- Model resolver: provider-prefixed `<provider>/<id>` selectors are now
strict. If the provider is known and the exact pair does not resolve,
return undefined instead of silently crossing provider boundaries
(e.g. routing `anthropic/claude-3-7-sonnet` to amazon-bedrock when
the user only has Anthropic auth). Unqualified resolution is unchanged.
- Compaction: when the current model's provider has no credentials,
manual compaction now retries across compaction model candidates and
falls back to an authenticated role; if no usable fallback exists, it
throws a clear provider-specific pre-stream error instead of bubbling
a 503 `auth_unavailable` from the provider stream.
Fixes#986Fixes#980
can1357