[Paul Lizer (paullizer)]

Summary

• Fix images, files, and restored document selections leaking into another V2 conversation during rapid navigation, including chips displaying document GUIDs instead of filenames.
• Retain unsent attachment selections in account/conversation-scoped tab memory. Guard late uploads, message/metadata loads, failed-send recovery, and stale Send handlers by ownership, navigation generation, and draft revision.
• Preserve upload-created conversation adoption and processing/retry behavior without moving or deleting stored files. Update the upload/context guidance and fix documentation, and bump the application to 0.261.411.

Linked issue

N/A. Issue creation was declined for this work.

Release Notes & Latest Features

• New Feature
• Bug Fix
• UI Enhancement
• Breaking Change
• Internal only

Is this visible to end users?

• Yes
• No

Is this admin-facing (Admin Settings, governance, deployment, config)?

• Yes
• No

Should this become a Latest Feature card?

• Yes
• No
• Already added

Screenshot needed for the card?

• Yes
• No
• Attached

Release notes remain unchanged pending user approval; no Latest Feature card is proposed.

Version bump

• application/single_app/config.py VERSION third segment bumped, or not needed because this is docs-only
• deployers/version.txt bumped, or not needed because deployers/ was not changed

Application version: 0.261.410 -> 0.261.411. No deployer changes.

Testing / validation

• node .\functional_tests\test_v2_chat_attachment_isolation.mjs - passed real ownership, recovery, adoption, scope, revision, and filename helper checks.
• npm --prefix .\application\v2_ui run build - passed TypeScript compilation and the production build; the existing bundle-size advisory remains.
• python -m pytest .\ui_tests\test_v2_new_chat_reset.py .\ui_tests\test_v2_chat_attachment_isolation.py -q --tb=short - 33 passed, including 26 new attachment-isolation scenarios. Coverage includes delayed responses, A-to-B-to-A navigation, successive null-ID drafts, interrupted/processing uploads, manual/Orchestrate payloads, and navigation plus Send in one event.
• python -m pytest .\functional_tests\test_v2_chat_context_picker.py .\functional_tests\test_v2_new_chat_reset.py -k "not orchestration_turns_record_their_streaming_surface_whatever_is_on_screen" -q --tb=short --disable-warnings - 16 passed, 1 deselected. The excluded legacy source-literal assertion also fails against the unmodified base commit.
• python .\functional_tests\test_docs_app_surface_coverage.py - 7/7 checks passed; inventory is current.
• python .\functional_tests\test_docs_site_quality.py - 6/6 documentation source checks passed.
• git -c core.whitespace=blank-at-eol,blank-at-eof,space-before-tab,cr-at-eol diff --check - passed before commit.

The original two browser reproductions failed before the fix and now pass. An exploratory affected-browser sweep passed all 133 test bodies but exposed four shared-fixture teardown errors for an unmocked pending-credential read. This PR supplies that expected empty response without relaxing error checks; both consuming suites were then re-run clean (33 passed above).

Known unrelated legacy limitations are documented in docs/explanation/fixes/V2_CONVERSATION_ATTACHMENT_ISOLATION_FIX.md: the obsolete orchestration-map assertion and closed namespaces missing backend locals in functional_tests/test_v2_prompt_attachment_persistence.py. The exploratory functional run had 64 passes and 37 failures from those existing harness problems; the affected backend routes and legacy harness are unchanged.

Documentation

• Release notes updated, or not needed
• Feature documentation updated, or not needed
• Fix documentation updated, or not needed

Updated the chat upload guide and context-picker documentation. Added the versioned attachment-isolation fix notes with behavior, root cause, validation evidence, and legacy harness limitations. Pending selections are tab-memory only; no server-side draft persistence or historical data repair is introduced.

Security checklist

• New Flask routes include @swagger_route(security=get_auth_security())
• Settings sent to non-admin frontends use sanitize_settings_for_user()
• Browser JavaScript is served from local SimpleChat static assets only; no CDN-hosted JS
• No secrets, keys, connection strings, or local-only artifacts are included

No Flask routes or settings payloads were added or changed. Filename hydration uses existing authorized, explicitly scoped document-detail readers, and filenames remain escaped React text. Existing source authorization is unchanged.