# Phase 3: Diagnostic Features - Discussion Log

> **Audit trail only.** Do not use as input to planning, research, or execution agents.
> Decisions are captured in CONTEXT.md — this log preserves the alternatives considered.

**Date:** 2026-04-12
**Phase:** 03-diagnostic-features
**Mode:** --auto (all decisions auto-selected)
**Areas discussed:** Delta highlighting, Idle compression, GIF export, Tool parameters

---

## Delta Highlighting Approach

| Option | Description | Selected |
|--------|-------------|----------|
| Red semi-transparent overlay | Highlight changed pixel regions with red overlay above threshold | ✓ |
| Side-by-side diff | Show previous and current frame side by side | |
| Border/outline marking | Draw boxes around changed regions | |

**User's choice:** [auto] Red semi-transparent overlay — visually obvious, standard approach
**Notes:** Fixed threshold (not user-configurable in v1). First frame has no overlay.

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## Idle Frame Compression

| Option | Description | Selected |
|--------|-------------|----------|
| Pixel comparison with tolerance | Compare buffers, collapse near-identical sequences with label | ✓ |
| Hash-based comparison | MD5/SHA hash of buffers for exact match only | |
| No compression | Keep all frames, just label idle periods | |

**User's choice:** [auto] Pixel comparison with tolerance — handles minor noise from compression artifacts
**Notes:** Label shows "unchanged for N.Ns". Uses first frame of sequence as representative.

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## GIF Export Interface

| Option | Description | Selected |
|--------|-------------|----------|
| Boolean flag on start_capture | gif_export: true produces GIF alongside grid | ✓ |
| Separate export tool | New export_gif tool called after capture complete | |
| Always generate GIF | Produce both formats automatically | |

**User's choice:** [auto] Boolean flag — configured at capture start, opt-in to avoid overhead
**Notes:** Exposed as separate resource at capture://{sessionId}/gif

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## Tool Parameter Design

| Option | Description | Selected |
|--------|-------------|----------|
| Flags on start_capture | Add delta_highlight, compress_idle, gif_export booleans | ✓ |
| Separate configure tool | Set diagnostic options via separate tool before capture | |
| Post-capture processing | Apply diagnostics when retrieving results | |

**User's choice:** [auto] Flags on start_capture — simple, everything configured upfront
**Notes:** All three are optional, default false. Stored in CaptureConfig.

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## Claude's Discretion

- Pixel comparison algorithm details
- Delta highlight color choice
- GIF color quantization
- Internal buffer handling

## Deferred Ideas

None