docs: explain chat attachment import into knowledge libraries

.project-docs/30-worklog/tasks/20261013-chat-knowledge-import-explain-ec03b792.md

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+# Task: Explain choosing chat attachments for a knowledge library
+
+## Identity
+
+- Task ID: 20261013-chat-knowledge-import-explain-ec03b792
+- Mode: Feature
+- Branch: codex/20261013-chat-knowledge-import-explain-ec03b792-chat-knowledge-import-explain
+- Worktree: /Users/chillishark/Makelore 麦洛/.codex-worktrees/makelore/20261013-chat-knowledge-import-explain-ec03b792
+- Base commit: c634425cc669f1da66e725649a386bf09661a70c
+- Owner: codex
+- Status: Ready for Integration
+
+## Scope
+
+- Explain the screenshot's "从聊天选择文件" entry, source-chat/file range, destination, processing and activation. Inspect committed client knowledge-workspace source c634425 and committed Yuxi reference source; no product edits.
+
+## Intent And Constraints
+
+- User requests a product-language explanation, not an import, redesign or app update. Preserve real files/chats/libraries, runtime, peer worktrees and source. Only this owned record changes.
+
+## Outcome
+
+- This entry copies already uploaded/confirmed attachments from the user's personal Agents chats into the own knowledge library selected on the left ("试试" in the screenshot). Source chat attachments remain in place.
+- Threads are loaded without a target-agent filter, so the user's eligible chats from other personal/shared Agents can be sources. Caller ownership is enforced by Yuxi; the target creator cannot import someone else's attachments.
+- Chat text and assistant-generated workdir files are not imported. The picker fetches attachments, not history or generated-file listings.
+- Latest committed picker supports searching chats/files, cross-chat selection, supported-document limits (5 MB; txt/md/csv/json/docx/xlsx/pdf), independent import receipts and same-operation failure retries.
+- Client onImported invokes processKnowledge; status polling confirms actual indexed chunks/availability before displaying "可用于回答". Selecting a library for an Agent changes configuration and requires explicit save/apply; import is not itself final activation.
+- Import reuses the knowledge upload/storage path, making a new knowledge copy without moving/deleting the chat original. Other eligible personal Agents can select the same own library.
+
+## Verification
+
+- Read source: CloudKnowledgeAttachmentPicker thread/attachment/selection/import flow, CloudKnowledgeDocuments onImported/processing callback and CloudKnowledge target selection; existing focused import test shows cross-chat attachment selection and no history/files/deleteAttachment calls.
+- Independent read-only Yuxi review confirms owned personal thread checking, confirmed attachment lookup, original file read/new upload, limits and separate assistant-generated file directory.
+- No application tests/build required for explanation-only source inspection; no real import, cloud mutation, file movement or runtime update performed.
+- Task-aware documentation drift and whitespace checks run at completion.
+
+## Follow-ups
+
+- Knowledge workspace peer source remains a separately owned completed feature; its recorded app update is deferred. This explanation does not authorize applying it or importing user files.
+
+## Promotion Candidates
+
+- None; current behavior explanation does not change accepted product semantics.
+
+## Project Context Loaded
+
+- Task ID/mode/branch/worktree/base match Identity and successful bundled start/status; managed isolated feature worktree, base c634425cc669f1da66e725649a386bf09661a70c.
+- Current context: prior entry/positioning/current-state/decision/architecture/domain/success-criteria knowledge rules rechecked; personal-cloud-agents ADR confirms own attachments, independent caller privacy, explicit configuration activation and processing readiness.
+- Peer Scope/Intent/Promotion sections read-only; knowledge-workspace ready source is the explicit verifiable base. Unknown legacy scopes have no concrete dependency for this explanation.
+- Goal: personal Agent knowledge reuse with Main-owned transport and Yuxi-owned permissions/storage. Relevant files: picker, documents, knowledge selection and Yuxi knowledge/conversation service.
+- Constraints: no user-file import, live UI operation, app refresh or product changes. Runtime deployment of the peer's newer picker is not inferred from a screenshot.
+- Gate result: Passed for read-only explanation; no coding plan or implementation needed.