fix(mailbox): show thread status and conversation history on every client

[pseudoseed]

Problem

Mailbox thread selection offered settled threads during search, linked threads lacked current status, and the mobile sheet obscured titles and rendered incorrectly in dark mode. Users could not inspect the full exchange between two agents as a conversation.

Change

Keep existing links visible, restrict the new-link picker to unsettled threads, and derive current status from live thread shells. Web/desktop and native mobile now expose pair conversation history with delivery states, reply and sending-turn references, full-history search, and complete JSON export. Pair/search filters apply on the server before pagination, and mobile export uses the existing native share handoff.

Scope and approval

The fork maintainer requested mailbox status/mobile parity, approved the conversation audit improvement, and explicitly authorized committing and merging after green CI. This PR contains that mailbox work; release versioning follows separately.

Verification

73 focused tests passed: 19 server mailbox behavior tests, 20 shared filtering/presentation/export tests, 31 native attachment/export tests, and 3 actual WebSocket transport tests. Affected contracts, client-runtime, server, web, and mobile typechecks and scoped lint/format passed.

A real iOS simulator run verified linked settled-thread retention, full titles/status, explicit light/dark modes, settled/archived/deleted picker exclusions, link/unlink, pair history, literal search beyond the initial page, reply and sending-turn lookup, older-page navigation, and Dismiss/Restore with pending count 11 → 10 → 11. A native export with search active exactly matched all 65 stored chronological records; viewing/searching/exporting created no read acknowledgements.

Web/desktop visual verification was blocked by an unavailable Browser automation host. Android runtime verification was unavailable because the SDK is not installed. System-theme switching and relay/tunnel end-to-end runs were not verified.

Before/after screenshots use the same isolated iOS fixture and explicit dark appearance. The before image renders the original mailbox component from the base commit; the verified implementation was restored before committing.

Before	After

Full verification report · Native export share sheet

Model: GPT-6.1-Sol. Harness: Codex in PseudoCode.

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	14.0 KiB	14.0 KiB	−21 B (−0.1%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.3 KiB	7.3 KiB	−9 B (−0.1%)	7.4 KiB	✅
Codex	Live turn WebSocket wire	6.7 KiB	6.7 KiB	−12 B (−0.2%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	57.6 KiB	57.6 KiB	0 B (0.0%)	66.4 KiB	✅
Codex	Live turn messages	9	9	0 (0.0%)	21	✅
Claude	Total thread wire	14.0 KiB	14.0 KiB	+1 B (+0.0%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.3 KiB	7.3 KiB	0 B (0.0%)	7.4 KiB	✅
Claude	Live turn WebSocket wire	6.7 KiB	6.7 KiB	+1 B (+0.0%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	58.4 KiB	58.4 KiB	0 B (0.0%)	66.4 KiB	✅
Claude	Live turn messages	9	9	0 (0.0%)	21	✅

Baseline: 10c8b2b · PR result: 5119ee4 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 116.3 KiB
• Claude decoded thread snapshot: 117.0 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.