# Phase 6: 页面几何与交互命中层 - 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:** 2026-05-22
**Phase:** 6-页面几何与交互命中层
**Areas discussed:** Geometry Coverage, Interaction Migration, Display Strategy, Geometry Precision

---

## Geometry Coverage

| Option | Description | Selected |
|--------|-------------|----------|
| `selection` | Prioritize selection geometry first | ✓ |
| `search / highlight / tap locate` | Prioritize other interaction geometry first | |
| `all` | Spread coverage across all consumers immediately | |

**User's choice:** `selection`
**Notes:** User additionally said the first two discussion areas should be fully done, so this is not a thin one-off patch.

---

## Interaction Migration

| Option | Description | Selected |
|--------|-------------|----------|
| `selection` | Migrate selection range / hit / display flow first | ✓ |
| `search hit` | Migrate search hit resolution first | |
| `highlight paint` | Migrate highlight painting first | |
| `tap locate` | Migrate tap / point locate first | |

**User's choice:** `selection`
**Notes:** The selection chain is the first reader interaction to move onto the geometry layer.

---

## Display Strategy

| Option | Description | Selected |
|--------|-------------|----------|
| `custom overlay` | Add a dedicated overlay for selection/highlight rendering | ✓ |
| `UITextView only` | Keep all display logic inside `UITextView` selection behavior | |
| `hybrid` | Use `UITextView` plus overlay only for a subset | |

**User's choice:** `custom overlay`
**Notes:** Overlay is preferred for selection presentation; `UITextView` should not remain the main black-box selection renderer.

---

## Geometry Precision

| Option | Description | Selected |
|--------|-------------|----------|
| `glyph 级精度` | Prefer precise glyph-level geometry and reverse mapping | ✓ |
| `block 级兼容` | Prefer coarse block-level compatibility first | |
| `balanced` | Stop at whatever precision is easiest to ship | |

**User's choice:** `glyph 级精度`
**Notes:** Compatibility remains a constraint, but precision is the target.

---

## the agent's Discretion

- Keep `search` / `highlight` / `tap locate` compatible with the same geometry layer, but do not make them the primary migration target for this phase.

## Deferred Ideas

- Broader interaction migration beyond selection can reuse the same geometry layer in later work.