feat(agents-mobile): session comments (desktop parity)

[balegas]

Summary

Brings session comments to agents-mobile, closing the parity gap with the desktop UI (comments shipped in #4551). Part of the agents-mobile ↔ agents-desktop parity track (follows #4564, #4553).

The mobile session timeline is a shared web component (SessionChatLogDomEmbed) rendered inside an Expo-DOM WebView, while the composer is native. Because the embed already merges comments via useEntityTimeline and renders CommentBubble, reading comment bubbles already worked on mobile — this PR adds the missing write, reply, and dedicated-view surface.

What's included

• Comment mode in the native composer. A compact Message / Comment toggle (top of the composer), shown only when the entity type declares the comments collection and the user has write access. Comment mode reuses the desktop's createSendCommentAction verbatim (optimistic insert + authenticated POST /collections/comments), disables attachments/slash, and posts plain-text comments. Editing a queued message resets to prompt mode (mirrors desktop) so the comment path can't hijack an edit.
• Tap-a-row-to-reply. A new optional Expo-DOM callback onRequestReplyToComment(target) is threaded SessionChatLogDomEmbed → EmbedApp → ChatLogView → EntityTimeline.onReplyToRow. Tapping "reply" on a timeline row forwards the SelectedCommentTarget (plain JSON) to the native shell, which switches the composer to comment mode, focuses the input, and shows a reply banner.
• Optimistic-comment bridge. The composer (native) and timeline (embed) run in separate JS contexts with separate stream dbs, so the optimistic row inserted on the native side isn't visible in the embed on its own. Still-pending comments are forwarded across the boundary and projected into the embed timeline (deduped by key against synced rows), mirroring the existing inlineQueuedMessages bridge — so a posted comment renders immediately. Their ~pending orders keep them in the same bottom band the shared query uses, so ordering matches desktop.
• Comments-only view. A new comments EmbedViewId renders buildCommentsTimeline (via a commentsOnly prop on the chat-log embed) with a comment-locked native composer, reachable from a new gated Comments entry in the session menu.

The shared agents-server-ui changes are additive and optional — desktop callers of ChatLogView (embed-only) are unaffected. No server / runtime changes.

Test plan

• @electric-ax/agents-mobile + @electric-ax/agents-server-ui — typecheck clean
• Full suites pass (server-ui 102, mobile 84), incl. the reused comments.test.ts (send action, buildCommentsTimeline, target encode/decode)
• ESLint + Prettier clean

No new automated tests: the new logic lives in deeply-integrated screens/providers, and neither package has a render harness for them (mobile has no component-render setup; server-ui only renders self-contained components). The reused comment primitives stay covered by comments.test.ts.

Known limitation

• Comments-only view target-click. Tapping a reply's timeline-row target snapshot doesn't scroll (that row isn't in the filtered comment list); tapping a comment target works. Target-click in the main chat view works fully. A "switch to full timeline + focus" bridge would close this.

🤖 Generated with Claude Code

[github-actions]

Electric Agents Desktop Builds

Build artifacts for commit 7f02888.

Platform	Status	Artifact
macOS Apple Silicon	Passed	DMG
macOS Intel	Passed	DMG
Windows x64	Passed	Installer
Linux x64	Passed	AppImage / deb

Workflow run

[codecov]

Codecov Report

❌ Patch coverage is 13.33333% with 26 lines in your changes missing coverage. Please review.
✅ Project coverage is 58.83%. Comparing base (c1310b9) to head (7f02888).
⚠️ Report is 7 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...agents-server-ui/src/components/views/ChatView.tsx	0.00%	21 Missing ⚠️
packages/agents-server-ui/src/embed/EmbedApp.tsx	0.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4587      +/-   ##
==========================================
+ Coverage   57.31%   58.83%   +1.52%     
==========================================
  Files         341      384      +43     
  Lines       39765    42510    +2745     
  Branches    11559    12183     +624     
==========================================
+ Hits        22791    25011    +2220     
- Misses      16934    17421     +487     
- Partials       40       78      +38     

Flag	Coverage Δ
packages/agents	72.82% <ø> (ø)
packages/agents-mcp	77.70% <ø> (?)
packages/agents-mobile	78.81% <ø> (ø)
packages/agents-runtime	82.62% <ø> (-0.05%)	⬇️
packages/agents-server	75.26% <ø> (-0.03%)	⬇️
packages/agents-server-ui	7.40% <13.33%> (+0.02%)	⬆️
packages/electric-ax	46.42% <ø> (ø)
packages/experimental	87.73% <ø> (?)
packages/react-hooks	86.48% <ø> (?)
packages/start	82.83% <ø> (?)
packages/typescript-client	91.83% <ø> (?)
packages/y-electric	56.05% <ø> (?)
typescript	58.83% <13.33%> (+1.52%)	⬆️
unit-tests	58.83% <13.33%> (+1.52%)	⬆️

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[github-actions]

Electric Agents Mobile Build

Local mobile checks ran for commit 7f02888.

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[claude]

Claude Code Review

Summary

Incremental review of commit 7f02888d4 since iteration 2. This commit is a focused follow-up that resolves both remaining open items: showStop now excludes comment mode on mobile, and formatReplyBannerLabel is deduplicated into shared lib/comments.ts with a unit test. The change is small, correct, and well-scoped — nothing new to flag.

Review of the new commit (7f02888)

• showStop fix is correct. SessionScreen.tsx:692 now prepends !commentMode && to the showStop predicate, mirroring desktop's MessageInput.tsx:223. commentMode is in scope (defined at :592), so in comment mode (including the dedicated Comments view) the Post button no longer silently becomes "Stop generating" while the agent runs. Resolves iteration-2 Important Working with Postgres WAL format from Elixir #1.
• formatReplyBannerLabel deduped cleanly. The helper moved to comments.ts:86 as an exported function and is imported by both MessageInput.tsx:14 and SessionScreen.tsx:31; the two local copies are deleted. Resolves iteration-2 Suggestion Working with Postgres WAL format from Elixir #1 and prevents future drift.
• Null-handling unified — a small robustness gain for mobile. The shared signature is SelectedCommentTarget | null (the desktop variant). Mobile's old copy took a non-null SelectedCommentTarget; the call site (SessionScreen.tsx:950) is already inside a commentMode && commentTarget && guard so it only ever passes non-null, but the shared null-safe version is strictly safer. Type-checks fine since widening a non-null arg to | null is sound.
• Test added. comments.test.ts covers the lowercase-first-char behavior and both fallback paths (null and blank label). The target() helper's { label }-only snapshot is valid against CommentSnapshotValue (only label is required). Good — exactly the kind of pure helper worth pinning.

No new correctness, security, or convention concerns. Both @electric-ax/agents-mobile and @electric-ax/agents-server-ui are private ("private": true), so no changeset is required. No server/runtime contract changes.

Issues Found

Critical (Must Fix)

None.

Important (Should Fix)

None — both iteration-2 Important/Suggestion items are now addressed.

Suggestions (Nice to Have)

Carried over from earlier iterations, still low priority and unchanged by this commit:

1. Silent no-op when comment send is unavailable — send() is a no-op when sendCommentAction is null. A dev-time warning or disabled affordance would make the failure mode visible.
2. Bridge test coverage — the optimistic-comment bridge (projectedComments dedup, the ~pending filter, the key-signature gate) remains untested (Codecov 0% patch). The new formatReplyBannerLabel test shows the pattern works well for the pure helpers; extracting and pinning the bridge's pure logic would be worthwhile if it grows.

Issue Conformance

No linked issue (soft warning per convention). PR body is thorough and accurate; scope matches. The one documented known limitation (comments-only view target-click doesn't scroll to non-comment rows) is acknowledged as a follow-up.

Previous Review Status

• Important Working with Postgres WAL format from Elixir #1 (showStop excludes comment mode): Addressed in 7f02888d4.
• Suggestion Working with Postgres WAL format from Elixir #1 (formatReplyBannerLabel duplication): Addressed — now shared and tested.
• Suggestion [Merged on #3] Write inserts, updates and deletes to Vaxine #2 (silent no-op), bridge test coverage: Unchanged; still low priority.

With these resolved, the PR looks ready from a correctness and conventions standpoint.

---

Review iteration: 3 | 2026-06-16

[balegas]

Thanks for the review — addressed in 7f02888.

Fixed

• Important Working with Postgres WAL format from Elixir #1 (showStop in comment mode). Added !commentMode to the showStop condition so the Post button on the comments surface (and the comments-only view) never becomes a Stop generating control while the agent is running — mirrors desktop MessageInput.tsx.
• Suggestion Working with Postgres WAL format from Elixir #1 (duplicated formatReplyBannerLabel). Moved it into shared lib/comments.ts (no React-Native dep) and import it on both desktop and mobile; removed both local copies. Added a unit test for it (lowercase-first-char + Reply fallback).

Deferred (reasoning)

• [Merged on #3] Write inserts, updates and deletes to Vaxine #2 silent no-op on unavailable send — unreachable in practice: comment mode is gated on commentsEnabled, and the composer is disabled when !db. A surfaced error would be cosmetic only.
• Postgres replication source TCP server #3 effect-race focus — benign as noted; net state is correct (prompt, no banner). Not worth the extra guard.
• Read from vaxine stream, send transactions to slot server #4 render harness / broader extraction — neither package has a component-render harness; reused primitives stay covered by comments.test.ts. The cheap part (extracting the pure label helper) is done + tested.

Verified locally: both packages typecheck, ESLint + Prettier clean, full suites pass (agents-server-ui 104, agents-mobile 84).

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[msfstef]

Looks reasonable but it needs a rebase and also I would appreciate screenshots/video for the feature