refactor(app): extract session share command owner

[Astro-Han]

Summary

Extract the session share/unshare command flow out of use-session-commands.tsx into a focused owner module.

Touched files:

• packages/app/src/pages/session/use-session-commands.tsx
• packages/app/src/pages/session/session-share-command.ts
• packages/app/src/pages/session/session-share-command.test.ts

Why

This is a #601 message-flow governance slice for the oversized use-session-commands.tsx file. The share/unshare clipboard, toast, and SDK flow was embedded inside the command registry hook, making that hook harder for another agent to scan. This PR moves that responsibility behind a small command owner with direct tests while preserving the public command behavior.

Related Issue

Refs #601.
Parent: #599.

Dependency Status

Independent flat PR on dev.

This PR does not depend on #667/#669/#670/#671/#672/#674/#675/#676/#677/#673 and does not touch files currently owned by those flat PRs. It should be reviewed as a standalone #601 command-owner extraction.

Review order: can be reviewed after #667 for governance context, but does not need to wait for the message-timeline stack or the SessionTurn short stack.

Human Review Status

Pending. A human should make the final merge decision after reviewing the final diff and verification evidence.

Review Focus

• Confirm use-session-commands.tsx still wires share/unshare commands to the same session id, existing share url, SDK client, language, and toast behavior.
• Confirm session-share-command.ts owns only share/unshare command behavior and browser clipboard fallback, not unrelated command groups.
• Confirm the test coverage locks existing-url copy, new share creation, share failure, copy failure, unshare success, and unshare failure.

Architecture Effect

• owner extracted
• verification added
• behavior preserved
• LOC reduced: use-session-commands.tsx 618 -> 548 physical LOC in this PR
• new extracted owner is 122 LOC, test file is 165 LOC

Risk Notes

Behavior is intended unchanged. Main risk is share/unshare toast or clipboard regression; the new tests cover existing-url copy, create-share copy, failure to create a share, clipboard failure, unshare success, and unshare failure. No visible UI, dependency, persistence, platform, updater, packaging, or permission change.

How To Verify

Install in new worktree: pass
bun install --frozen-lockfile

Focused tests: 8 pass, 0 fail
bun test --preload ./happydom.ts src/pages/session/session-share-command.test.ts src/pages/session/use-session-commands.test.ts

Typecheck: 8 successful, 8 total
bun run typecheck

Diff check: pass
git diff --check

Screenshots or Recordings

Not applicable. This is a behavior-preserving command-owner extraction with no visible UI or copy change.

Checklist

• Human review status is stated above as pending, approved, or not required
• I linked the related issue, or stated why there is no issue
• This PR has type, primary area, and priority labels, or I requested maintainer labeling
• I described the review focus and any meaningful risks
• I listed the relevant verification steps and the key result for each
• I did not introduce unrelated refactors, dependencies, generated files, or file changes beyond the stated scope
• I manually checked visible UI or copy changes when needed, with screenshots or recordings
• I considered macOS and Windows impact for platform, packaging, updater, signing, paths, shell, or permissions changes
• I called out docs, release notes, dependencies, permissions, credentials, deletion behavior, generated content, or local file changes when relevant
• I reviewed the final diff for unrelated changes and suspicious dependency changes
• I am targeting dev, and my PR title and commit messages use Conventional Commits in English

[gemini-code-assist]

Warning

You have reached your daily quota limit. Please wait up to 24 hours and I will start processing your requests again!

[coderabbitai]

Warning

Rate limit exceeded

@Astro-Han has exceeded the limit for the number of commits that can be reviewed per hour. Please wait 48 minutes and 8 seconds before requesting another review.

You’ve run out of usage credits. Purchase more in the billing tab.

⌛ How to resolve this issue?

After the wait time has elapsed, a review can be triggered using the @coderabbitai review command as a PR comment. Alternatively, push new commits to this PR.

We recommend that you space out your commits to avoid hitting the rate limit.

🚦 How do rate limits work?

CodeRabbit enforces hourly rate limits for each developer per organization.

Our paid plans have higher rate limits than the trial, open-source and free plans. In all cases, we re-allow further reviews after a brief timeout.

Please see our FAQ for further information.

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: 900e0fa6-42bf-4b5d-8957-ec2fc93387cf

📥 Commits

Reviewing files that changed from the base of the PR and between 03140f7 and 7d0c343.

📒 Files selected for processing (3)

• packages/app/src/pages/session/session-share-command.test.ts
• packages/app/src/pages/session/session-share-command.ts
• packages/app/src/pages/session/use-session-commands.tsx

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/session-commands-share-owner

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[github-actions]

Suggested priority: P2 (includes user-path files (packages/app/src/pages/session/session-share-command.test.ts, packages/app/src/pages/session/session-share-command.ts, packages/app/src/pages/session/use-session-commands.tsx)).

P1/P0 are reserved for maintainer confirmation. Please relabel manually if this is a release blocker, security issue, data-loss risk, or updater/runtime failure.

[github-actions]

Perf delta summary

Comparator: pass

Profile / Scenario	interaction median	interaction worst	long task max	tbt	frame gap p95	frame gap max	jank count	cls	status
default / homepage-cold	32 -> 24 (-8)	48 -> 64 (+16)	78 -> 62 (-16)	28 -> 12 (-16)	33.4 -> 16.8 (-16.6)	150 -> 133.4 (-16.6)	3 -> 3 (0)	0 -> 0 (0)	pass
default / long-session-input-lag	48 -> 48 (0)	48 -> 72 (+24)	0 -> 0 (0)	0 -> 0 (0)	16.7 -> 16.7 (0)	16.8 -> 16.8 (0)	0 -> 0 (0)	0 -> 0 (0)	pass
default / session-streaming-long	48 -> 48 (0)	64 -> 56 (-8)	0 -> 0 (0)	0 -> 0 (0)	33.3 -> 16.8 (-16.5)	33.4 -> 33.3 (-0.1)	0 -> 0 (0)	0 -> 0 (0)	pass
default / tool-call-expand	16 -> 16 (0)	16 -> 24 (+8)	0 -> 0 (0)	0 -> 0 (0)	16.8 -> 16.7 (-0.1)	16.8 -> 16.7 (-0.1)	0 -> 0 (0)	0 -> 0 (0)	pass
default / tool-default-open-heavy-bash	24 -> 24 (0)	24 -> 24 (0)	63 -> 64 (+1)	13 -> 15 (+2)	50 -> 50 (0)	116.7 -> 100 (-16.7)	2 -> 2 (0)	0 -> 0 (0)	pass
default / terminal-side-panel-open	48 -> 40 (-8)	56 -> 48 (-8)	0 -> 0 (0)	0 -> 0 (0)	33.4 -> 33.3 (-0.1)	33.4 -> 33.3 (-0.1)	0 -> 0 (0)	0 -> 0 (0)	pass
default / session-scroll-reading	24 -> 16 (-8)	32 -> 24 (-8)	0 -> 0 (0)	0 -> 0 (0)	16.8 -> 16.8 (0)	16.8 -> 16.8 (0)	0 -> 0 (0)	0.505 -> 0.505 (0)	warn: cls
low-end / session-scroll-reading-long	64 -> 64 (0)	72 -> 88 (+16)	69 -> 85 (+16)	48 -> 53 (+5)	16.8 -> 16.8 (0)	66.7 -> 200 (+133.3)	3 -> 4 (+1)	0.016 -> 0.016 (0)	warn: frame_gap_max_ms_delta
low-end / session-timeline-recompute	136 -> 120 (-16)	136 -> 136 (0)	109 -> 106 (-3)	189 -> 171 (-18)	83.4 -> 100 (+16.6)	183.3 -> 183.3 (0)	4 -> 3 (-1)	0.081 -> 0.081 (0)	pass
low-end / concurrent-shimmer-extreme	0 -> 0 (0)	0 -> 0 (0)	0 -> 0 (0)	0 -> 0 (0)	16.8 -> 16.8 (0)	33.4 -> 16.8 (-16.6)	0 -> 0 (0)	0 -> 0 (0)	pass

[Astro-Han]

@coderabbitai review

[coderabbitai]

✅ Actions performed

Review triggered.

Note: CodeRabbit is an incremental review system and does not re-review already reviewed commits. This command is applicable only when automatic reviews are paused.