---
phase: 08-pagination-quality-cache-performance
plan: 03
type: execute
wave: 1
depends_on: []
files_modified:
  - Sources/RDReaderView/EPUBTextRendering/RDEPUBTextRendererSupport.swift
autonomous: true
requirements:
  - QUAL-04
must_haves:
  truths:
    - "Pagination timing is logged with chapter ID, page count, and elapsed milliseconds"
  artifacts:
    - path: "Sources/RDReaderView/EPUBTextRendering/RDEPUBTextRendererSupport.swift"
      provides: "Pagination timing instrumentation in existing rendering path"
      contains: "[EPUB][Perf]"
  key_links:
    - from: "RDEPUBTextRendererSupport"
      to: "os.signpost / print"
      via: "timing instrumentation"
      pattern: "\\[EPUB\\]\\[Perf\\]"
---

<objective>
Add performance sampling and diagnostic output to the pagination pipeline: log chapter ID, page count, and elapsed time for each pagination pass. This provides the baseline data needed to detect regressions and validate that quality improvements don't degrade performance.

Purpose: QUAL-04 requires that pagination improvements don't significantly degrade first-screen time, re-pagination time, or interaction smoothness. Without measurement, this can't be verified.

Output: Timing instrumentation in the existing rendering path with `[EPUB][Perf]` log prefix.
</objective>

<execution_context>
@$HOME/.claude/get-shit-done/workflows/execute-plan.md
@$HOME/.claude/get-shit-done/templates/summary.md
</execution_context>

<context>
@.planning/PROJECT.md
@.planning/ROADMAP.md
@.planning/STATE.md
@.planning/phases/08-pagination-quality-cache-performance/08-CONTEXT.md
@.planning/phases/08-pagination-quality-cache-performance/08-RESEARCH.md

<interfaces>
<!-- Key types the executor needs -->

From RDEPUBTextRendererSupport.swift:
- The main pagination entry point processes a chapter HTML string and produces an array of pages
- Existing logging pattern: `print("[EPUB][Attachment] footnote classes=...")`
- Use the same `print("[EPUB]...")` convention for consistency

From RDEPUBDTCoreTextRenderer.swift:
- `RDEPUBTextChapterRenderRequest` contains chapter identification
- Rendering produces `NSAttributedString` per page
</interfaces>
</context>

<tasks>

<task type="auto">
  <name>Task 1: Add pagination timing instrumentation</name>
  <files>Sources/RDReaderView/EPUBTextRendering/RDEPUBTextRendererSupport.swift</files>
  <read_first>
    - Sources/RDReaderView/EPUBTextRendering/RDEPUBTextRendererSupport.swift (full file — find the main pagination entry point)
    - Sources/RDReaderView/EPUBTextRendering/RDEPUBDTCoreTextRenderer.swift (understand render request flow and chapter identification)
  </read_first>
  <action>
Add timing instrumentation to the pagination pipeline in `RDEPUBTextRendererSupport.swift`.

**What to instrument:** The function that takes chapter HTML and produces paginated output (the main entry point called by the renderer). Wrap the core pagination logic with `CFAbsoluteTimeGetCurrent()` before and after.

**What to log:** After pagination completes, print a single diagnostic line:
```
[EPUB][Perf] chapter={chapterIdentifier} pages={pageCount} elapsed={milliseconds}ms
```

Where:
- `chapterIdentifier` = the chapter href or file name passed into the rendering request
- `pageCount` = number of pages produced
- `milliseconds` = elapsed time as a rounded integer

**Implementation approach:**
1. At the top of the pagination function, capture `let startTime = CFAbsoluteTimeGetCurrent()`
2. At the end (after pages are produced), compute `let elapsed = Int(round((CFAbsoluteTimeGetCurrent() - startTime) * 1000))`
3. Print: `print("[EPUB][Perf] chapter=\(chapterID) pages=\(pages.count) elapsed=\(elapsed)ms")`

Use the same logging convention as the existing `[EPUB][Attachment]` logs. If the function already has a chapter identifier parameter, use it directly. If not, extract it from the request context.

Do NOT add `os.signpost` or `OSLog` — keep it simple with `print` to match existing project conventions. A more sophisticated logging system can be added in Phase 9.
  </action>
  <verify>
    <automated>xcodebuild build -project ReadViewDemo/ReadViewDemo.xcodeproj -scheme ReadViewDemo -destination 'platform=iOS Simulator,name=iPhone 16' 2>&1 | tail -5</automated>
  </verify>
  <acceptance_criteria>
    - RDEPUBTextRendererSupport.swift contains `CFAbsoluteTimeGetCurrent()` for timing capture
    - RDEPUBTextRendererSupport.swift contains `print("[EPUB][Perf]` diagnostic output
    - Diagnostic line includes chapter identifier, page count, and elapsed milliseconds
    - xcodebuild build exits 0
  </acceptance_criteria>
  <done>Pagination timing instrumentation is in place, build compiles, diagnostic log line fires after each chapter pagination</done>
</task>

</tasks>

<verification>
- Build succeeds
- Running the demo app produces `[EPUB][Perf]` log lines in the console after navigating between chapters
</verification>

<success_criteria>
- Each pagination pass logs chapter ID, page count, and elapsed time
- Log format is consistent with existing `[EPUB]` convention
- No performance overhead beyond a single `CFAbsoluteTimeGetCurrent()` call (negligible)
</success_criteria>

<output>
Create `.planning/phases/08-pagination-quality-cache-performance/08-03-SUMMARY.md` when done
</output>