feat: show copyable session ID in session detail header

[shreyaskarnik]

Summary

• Adds a clickable session ID to the session detail breadcrumb bar
• Shows first 8 characters of the session ID in a monospace styled element
• Hovering shows the full session ID as a tooltip
• Clicking copies the full session ID to clipboard with "Copied!" feedback (1.5s)
• Extracted a reusable copyToClipboard utility with tests

This lets users easily grab session IDs for claude --resume <id>.

Demo

Screen.Recording.2026-02-24.at.3.05.41.PM.mov

Tests Ran

• copyToClipboard utility tested (success + failure paths)
• All 383 frontend tests passing
• Go tests passing (no backend changes)
• Manual: navigate to session, verify truncated ID visible
• Manual: hover shows full ID tooltip
• Manual: click copies full ID, shows "Copied!" for 1.5s

🤖 Generated with Claude Code

[roborev-ci]

roborev: Combined Review (e49851c)

Summary Verdict: All agents agree the code is clean; no medium, high, or critical issues were found.

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Synthesized from 4 reviews (agents: codex, gemini | types: default, security)

[shreyaskarnik]

@wesm awesome project, after couple of uses figured that the project can show session id for fast resume functionality

[shreyaskarnik]

Note: just noticed #14 has overlap here - it adds a keyboard shortcut (c) and header button to copy a full CLI continue command for the active session. Our PR focuses on making the session ID visible in the breadcrumb bar with click-to-copy.

If #14 covers the use case sufficiently (copying a ready-to-use CLI command), happy to close this in favor of that. Let us know @wesm!

[roborev-ci]

roborev: Combined Review (ce53634)

The PR introduces a severe Svelte syntax error that will break the
build, alongside a medium-severity UI state bug with the copy timeout.

High

• Svelte syntax error
  • File: frontend/src/App.svelte (Line 203)
  • Problem: The space in { @const ...} causes Svelte to parse
    the block as an invalid JavaScript expression instead of the special {@const tag, which will break the Vite build.
  • Fix: Remove the space: {@const rawId = sessionDisplayId(session.id)}.

Medium

• Copied state can clear too early on repeated
  clicks of the same session
  • File: frontend/src/App.svelte (Line 209)
  • Problem: Each successful click creates a new setTimeout, but timers are keyed only by session.id. If the same session is clicked again before the first
    timer fires, the older timer still matches and clears "Copied!" earlier than intended.
  • Fix: Track and clear a per-component timeout handle before starting a new one, or use a monotonic token/counter per click and only clear for the latest token.

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Synthesized from 4 reviews (agents: codex, gemini | types: default, security)

[wesm]

review not valid. merging