RFC: package host session import outside the main package

[PsiACE]

PR #1602 proposes importing historical Codex prompts. Require a focused RFC before adding more hosts, so host-specific parsing and identity rules can live in integration packages without changes to the main package.

The proposed responsibility split is:

Codex adapter              Other host adapters
parse / filter             parse / filter
identity / bindings        identity / bindings
      |                            |
      +-------------+--------------+
                    |
                    v
         Shared import workflow
         capture / retry / checkpoint
         reuse existing client support
                    |
                    v
       Existing capture / ingestion APIs
                    |
                    v
           Persisted Sources
                    |
                    v
        Existing server processing
       scheduled or explicitly requested

The shared workflow is a proposed code boundary. The RFC should determine how much existing implementation it can reuse. Import completion means Sources were accepted; extraction follows the Server’s processing policy.

Existing foundations:

• RFC 1400 and RemoteConnectorWorker cover remote ingestion and Connector checkpoints.
• The client SDK supports Content Source capture and Scope resolution. The CLI supports command entry points.

The RFC should decide:

1. Adapter packaging, command registration, and shared workflow ownership.
2. Whether to retain Content Source capture or adapt the Connector lifecycle, preserving live-capture identity and defining skipped-item behavior.
3. How each host shares identity and metadata construction between live capture and historical import.

Acceptance: another host can implement session import without adding host-specific branches to the main package, while preserving idempotency and recovery.

Server processing changes and fine-grained import controls are outside scope. Accept the RFC before implementing this shared architecture or extending the workflow to a second host.