research(work): evaluate Source-backed working notes separate from Memory #1790

Feature description

Evaluate Source-backed working notes as session-local work state, separate from Memory.

Codex added history and notes tools for token-budget sessions. PowerContext should evaluate whether there is a PC-native equivalent for short-lived working notes, but keep the boundary clear: working notes are not durable Memory, not agent instructions, and not a substitute for Handoff.

Codex prior art to review:

• Add history and notes tools for token-budget sessions openai/codex#39827 - Add history and notes tools for token-budget sessions
• Inject history notes hints into context windows openai/codex#40539 - Inject history notes hints into context windows

Problem and proposed solution

During long work, there are useful intermediate notes that are too temporary for Memory but still useful as evidence for a later Handoff:

• inspected files and why they mattered;
• abandoned approaches;
• local validation commands and outcomes;
• unresolved questions or assumptions;
• host-specific context that should be omitted if not captured.

PowerContext needs a product decision for this layer. It may be enough to model these as Source records with a working-note kind; or it may require an Artifact/RFC later. This issue is to evaluate and define the smallest compatible approach.

Proposed constraints:

• Working notes must be explicitly captured by a host/user flow.
• They must be citeable as Handoff evidence.
• They must not automatically promote into Memory.
• They must have retention/access-control behavior consistent with Source.
• They must not be exposed as agent-executable instructions.

Alternatives considered

• Create a new durable Notes family immediately. This may duplicate Handoff and Source before the use case is proven.
• Put working notes in Memory. That would pollute long-term memory with transient progress.
• Keep notes only in host transcripts. That loses cross-host continuity and evidence checking.

Additional context

Related PowerContext work:

• PR RFC: Handoff session rollover #1783: Rollover Handoff.
• RFC: package host session import outside the main package #1680: package host session import outside the main package.
• tracking(continuity): 宿主历史导入与可评估的上下文连续性 #1574: host history import and context continuity.

Acceptance criteria:

• The issue produces a design decision: Source-kind only, new Artifact family, or no feature.
• The decision includes retention, access, citation, and Memory-promotion boundaries.
• If implemented, working notes can support Handoff generation without weakening evidence requirements.