feat(assistant): simplify workspace, sources and saved artifacts

[chaxus]

Summary

Make the document AI workspace compact and predictable: preserve drafts and reading position, explain failures, keep source context explicit, and review changes before applying them.

• Flatten the composer, collapsed queue, result actions and model settings. Preserve caret/focus/scroll across views and conversations, highlight conversation/source searches, provide truthful local action feedback, and stage follow-ups without sending or replacing a draft implicitly.
• Add bounded standalone DOCX/XLSX/PPTX/PDF references, explicit MCP resource pagination and optional Google Drive filename search. Resolve citations only against the actual excerpts sent for that response, including persisted conversations. Keep cancellation, offline operation and expired authorization actionable.
• Add versioned text/table/slides artifacts with provenance, editable structured fields, reviewed AI revisions, conflict recovery and offline TXT/Markdown/CSV/JSON export. Keep native changes behind existing review, add exact Excel/PPT location and conditional Undo for proven owned Word pastes, and summarize actual task outcomes.

Design and architecture

Use a continuous canvas, one composer boundary and progressive disclosure. Separate source discovery/readers, request evidence, navigation, artifact payload/storage/editor/proposals, queue leases and native receipt ownership. Generic chat/runtime extensions remain host-independent; no second runtime or UI framework. Vendor SDK bundles remain untouched.

Capability boundaries

• Google OAuth is optional and not configured by the deployment owner yet. Server-side credential setup, real consent and live Drive reads remain unverified; mocked tests do not claim otherwise. See deployment and live-validation guide.
• MCP supports read-only Streamable HTTP resources; arbitrary MCP tools/stdio are outside this implementation. Standalone references enforce extraction budgets and do not perform OCR or replace the current editor.
• Structured artifacts export offline. Native table/slides application and standalone Office artifact export remain unavailable where no verified atomic/conversion contract exists; text artifacts retain Word review. No arbitrary generated HTML/JS executes.
• Custom Undo is limited to an exclusive, fully committed local Word paste with exact history proof; later edits, Undo/Redo, document replacement or missing capabilities refuse it. Word lacks a proven durable native anchor, so it uses truthful scope/diff feedback rather than fabricated highlights.

Verification

• 6,166 unit tests / 229 files passed; all coverage thresholds passed (statements 86.74%, branches 82.88%, functions 87.49%, lines 89.29%).
• 40 integrated browser scenarios passed across composer/navigation, history, request queues, sources/artifacts, standalone references, AI revisions and native writes/tasks.
• Full lint/TypeScript, format/1,511 immutable archive checks, and production build passed. Actual light/dark/narrow screenshots inspected, including prepared offline reload.
• Regression fixes cover per-operation source ownership, auth/disconnect races, save/cancel outcomes, async draft acceptance, origin-safe queue recovery, structured persistence/exports, and exact commit-to-Undo ownership.

Final review status

[APPROVE] — Overall review completed after latest-head CI passed, including a final recheck of all review fixes. No outstanding blocking findings were identified in the reviewed scope.

• Reviewed head: 1a35114a3fa7e598c1cbbca0ed4a8e949245a653; all 19 remote checks passed.
• Three review partitions covered core orchestration/native ownership, source/artifact domains and crosscutting deployment/docs/tests. Changed contracts were traced through their consumers.
• Fixed and rechecked disclosure reopening, direct-apply receipt disposal, attached references in built-in read tasks and stale reader documentation. Full local verification was rerun after those fixes.
• Google live OAuth remains externally pending as described above.

[cloudflare-workers-and-pages]

Deploying document with    Cloudflare Pages

Latest commit:	1a35114
Status:	✅  Deploy successful!
Preview URL:	https://3c2dc186.document-7hm.pages.dev
Branch Preview URL:	https://fix-assistant-readiness-feed.document-7hm.pages.dev

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