K8s sandbox recording fix + TUI render-cache with collision prevention - #506
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Performance fix for TUI slowdown in long sessions. Three changes:
1. Per-item render cache (app.go)
- Add renderedBlock struct caching padded+painted block, plain-text
lines, and content spans per finalized transcript item
- itemRenderCache map[string]renderedBlock on model, keyed by
width+kind+content+expanded+routing
- Streaming/provisional items bypass the cache
- Cache cleared on WindowSizeMsg (terminal resize)
- Eliminates re-running padBlock->applySelectionToBlock->
paintTranscriptBlock->ANSI-strip for every historical item on
every refreshViewport()
2. Selection-scoped highlight application (selection.go, app.go)
- Add selectionIntersectsLines() helper method
- Gate applySelectionToBlock() to only blocks whose line range
intersects the active selection
- Drag selection is now O(selected blocks) not O(all items)
3. Mouse-motion refresh debounce (app.go)
- Rate-limit refreshViewport() in handleMouseMotion to 16ms (~60fps)
- Prevents CPU saturation from high-frequency terminal mouse events
Benchmark (200-item session, Apple M4 Pro):
BenchmarkRenderTranscript200Items/warm_cache: ~2.3ms/op
BenchmarkRenderTranscriptWithSelection: ~1.25ms/op
Tests: all pkg/tui/... pass; new TestSelectionIntersectsLines added;
TestWindowResizeClearsMarkdownCache updated to cover itemRenderCache.
Fixes the xdpyinfo error 'probe display size: no dimensions in xdpyinfo output' when running drills with browser_start_recording on Kubernetes. The root cause is that kubectl exec runs commands in the pod base namespace (thin Debian image) rather than inside the chroot overlay at /sandbox/rootfs where xdpyinfo, ffmpeg, and other tools are installed. Solution: Added backendShellCommand() helper that wraps shell commands through /usr/local/bin/astonish-shell on K8s backends (which chroots into /sandbox/rootfs), while using plain sh -c on Docker (where overlay is root). This mirrors the pattern already established in backend_mcp_transport.go for MCP transport. Applied wrapper to all 4 exec calls in startBackendRecording: - Display probe (xdpyinfo) - mkdir for recording output directory - ffmpeg start script - ffmpeg stop script Added unit tests: - TestBackendShellCommand_Docker: Docker uses plain sh -c - TestBackendShellCommand_K8s: K8s uses astonish-shell wrapper - TestBackendShellCommand_NilBackend: nil backend defaults to Docker mode - TestStartBackendRecording_K8sUsesAstonishShell: E2E test of recording flow All sandbox package tests pass.
Fixes visual-correctness issues identified in PR review where two activities with identical summaries but different steps (e.g., 'Read 1 file' reading different files) could display the wrong transcript block due to cache-key collisions. Changes: - Add stepsCacheDigest(), argsCacheDigest(), resultCacheDigest() helpers that compute stable FNV-1a hashes of step fields for cache-key inclusion. - Include step digest in activity cache key to prevent collisions on identical summaries. - Include ToolName and args digest in file-diff cache key when DiffVerification is empty (fallback path to DiffFromToolArgs). - Add TestActivityCollisionPrevention regression test verifying two activities with same summary but different steps have different cache keys and render distinct output. - Add TestFileDiffCollisionPrevention regression test verifying two file-diffs with same content but different args have different cache keys and render distinct output. All TUI tests pass; no regressions.
Four changes addressing review comments on #506: 1. De-duplicate agent badge rendering (Medium issue) Extract applyRoutingBadge(md, cw, it) helper method. Both the streaming bypass path and the finalized/cacheable path now call this single helper, guaranteeing the streaming and finalized bubbles render identically. Eliminates 25-line copy-paste that could silently diverge. 2. Bound/evict itemRenderCache after each render pass (Medium issue) Track usedCacheKeys in each renderTranscript call. After the for loop, delete any map entry not referenced in this pass. This prevents unbounded growth from orphaned entries (opposite expand/collapse states, items removed by /compact). The cache is now bounded to at most len(tr.Items) entries after every render. 3. Harden TestWindowResizeClearsMarkdownCache (Minor) Replace the t.Skip("cache key format changed") guard with an explicit prefix scan: any key starting with the old-width prefix ("80\x00") in either mdCache or itemRenderCache after resize fails the test loudly. A future key-format change now errors instead of silently skipping. 4. Fix hash formatting and rune-safe truncation (Minor) - strconv.FormatInt(int64(hash), 16) -> FormatUint(hash, 16): avoids negative-looking hex for high uint64 values. - argsCacheDigest / resultCacheDigest truncation now uses []rune slicing to avoid splitting a multi-byte UTF-8 rune mid-character.
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Overview
This PR contains two complementary features: a K8s sandbox recording fix and a TUI transcript render-cache optimization with collision prevention.
1. K8s Sandbox Recording Fix (K8s xdpyinfo error)
Problem: When running
run_drillwith browser recording enabled on Kubernetes, drills failed with:Root cause:
kubectl execruns commands in the pod's base namespace (thin Debian image), not inside the chroot overlay at/sandbox/rootfswherexdpyinfo,ffmpeg, and other tools are installed.Solution: Added
backendShellCommand()helper that wraps shell commands through/usr/local/bin/astonish-shellon K8s backends (which chroots into the overlay), while using plainsh -con Docker (where overlay is root). Mirrors the pattern inbackend_mcp_transport.go.2. TUI Render-Cache with Collision Prevention
Performance optimization: Added item render cache that memoizes fully-rendered transcript blocks. Reduces rendering cost from O(all items) to O(new/changed items) on each viewport refresh. Includes smart caching guards for streaming/interactive items and per-item selection application.
Visual-correctness fixes: Identified and fixed two collision bugs from PR review:
DiffVerificationbut different args could collide. Fixed by including ToolName and args digest in cache key when using fallback rendering path.Added regression tests:
TestActivityCollisionPreventionverifies activities with same summary but different steps don't collide.TestFileDiffCollisionPreventionverifies file-diffs with different args don't collide.Changes
K8s Recording Fix
pkg/sandbox/backend_browser_wire.go: AddedbackendShellCommand()helper, wrapped 4 exec calls instartBackendRecording()pkg/sandbox/backend_browser_wire_test.go: Added unit tests for wrapper behavior and end-to-end K8s recording testTUI Render-Cache
pkg/tui/app.go: Added cache digest helpers, included digests in activity and file-diff cache keyspkg/tui/app_render_test.go: Added collision regression testsBackward Compatibility
✅ Docker backend behavior unchanged
✅ OpenShell backend unaffected
✅ Non-cached item types unaffected
✅ Breaking changes: None
Tests