---
phase: 02-vault-core-and-rendering
plan: 02
subsystem: renderer
tags: [pulldown-cmark, ratatui, syntax-highlighting, cga-colors, box-drawing, markdown-rendering]

dependency_graph:
  requires:
    - phase: 02-01
      provides: highlight_code(), OnceLock-based syntect initialization, CGA color mapping
  provides:
    - render_markdown() — markdown string to Vec<Line<'static>> conversion pipeline
    - H1-H6 heading rendering with CGA colors and ═/─ decorators
    - Bold/italic/inline code inline styling
    - Ordered and unordered list rendering with ●/◦/▪ bullets
    - Blockquote rendering with yellow │ border
    - Horizontal rule rendering (full-width ─ in DarkGray)
    - Image placeholder rendering [IMAGE: alt]
    - Fenced code block rendering with ╭─╮│╰─╯ borders + syntect highlighting
    - GFM table rendering with ┌┬┐├┼┤└┴┘ full box-drawing grid
  affects: [02-03-app-integration]

tech-stack:
  added: []
  patterns:
    - RenderState struct with style_stack (Vec<Style>) for nested inline formatting
    - Two-pass table rendering: accumulate all cells, then emit box-drawing grid
    - TextMergeStream wrapping Parser::new_ext to coalesce adjacent Text events
    - emit_code_block() and emit_table() as standalone free functions called by RenderState methods
    - All Span content uses .to_string() for owned strings — Vec<Line<'static>> with no lifetime leakage

key-files:
  created:
    - src/renderer.rs
  modified:
    - src/main.rs

key-decisions:
  - "Wrote full emit_code_block and emit_table implementations in Task 1 rather than stubs — stubs would have been discarded in Task 2; single pass was cleaner"
  - "Removed unused push_fg and push_fg_mod helper methods — start_heading() constructs styles inline, keeping RenderState API minimal"
  - "emit_code_block box_width computed as max(content_width + 4, lang.len() + 6) capped at terminal width — prevents border overflow on long lines"
  - "Table n_cols derived from max(alignments.len(), max row length) — handles malformed tables with mismatched column counts gracefully"

patterns-established:
  - "RenderState pattern: internal struct with push/pop style_stack, flush_line() accumulates then emits, finish() returns owned Vec<Line<'static>>"
  - "Box-drawing code blocks: ╭─ lang ─╮ / │ content padding │ / ╰─╯ with DarkGray borders and Yellow lang label"
  - "Box-drawing tables: ┌┬┐├┼┤└┴┘ with Cyan border_style and LightCyan+BOLD header row"

requirements-completed: [REND-01, REND-02, REND-03, REND-04, REND-05, REND-06, REND-07, REND-08, REND-09, REND-10]

duration: 4min
completed: 2026-02-28
---

# Phase 02 Plan 02: Markdown Renderer Summary

**pulldown-cmark event pipeline producing Vec<Line<'static>> with CGA-colored headings, syntax-highlighted fenced code blocks with ╭─╮│╰─╯ borders, and GFM tables with ┌┬┐├┼┤└┴┘ box-drawing grids**

## Performance

- **Duration:** 4 min
- **Started:** 2026-02-28T21:15:20Z
- **Completed:** 2026-02-28T21:19:00Z
- **Tasks:** 2
- **Files modified:** 2 (src/renderer.rs created, src/main.rs updated)

## Accomplishments

- Complete `render_markdown(input: &str, width: u16) -> Vec<Line<'static>>` public function
- All Phase 2 REND-01 through REND-10 requirements implemented in one module
- Code blocks render with rounded box-drawing borders (╭─ lang ─╮ / │ │ / ╰──╯), language label in Yellow, content via `crate::highlighter::highlight_code()`
- GFM tables render with full DOS-style box grid (┌┬┐├┼┤└┴┘), bold LightCyan header row, Left/Right/Center column alignment

## Task Commits

1. **Task 1: Build core markdown renderer with inline and block elements** - `9e6f79c` (feat)
2. **Task 2: Add code block borders with syntax highlighting and GFM table grid** - `8690d2a` (feat)

## Files Created/Modified

- `src/renderer.rs` — Complete markdown-to-styled-lines conversion pipeline (717 lines); `render_markdown()` public API; `RenderState` internal struct with style stack, blockquote depth, list counters, two-pass table collection; `emit_code_block()` and `emit_table()` free functions
- `src/main.rs` — Added `mod highlighter; mod renderer; mod vault;` declarations (wiring for Plan 03)

## Decisions Made

- Implemented full emit_code_block and emit_table in Task 1 rather than writing throwaway stubs — since both functions were already designed in the plan, writing real code once was cleaner than writing placeholder code twice
- Removed `push_fg` and `push_fg_mod` helper methods from RenderState after they proved unused — `start_heading()` constructs styles directly with `.fg().add_modifier()` inline
- Box width for code blocks capped at terminal `width` parameter to prevent overflow when code lines are longer than the terminal
- Table column count derived from `max(alignments.len(), max row cell count)` to handle pathological GFM tables with mismatched header/data column counts

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 1 - Bug] Fixed type inference error in list item bullet computation**
- **Found during:** Task 1 (cargo check feedback)
- **Issue:** `let (bullet_str, new_counter) = match ...` with `None` literals caused `E0282: type annotations needed for Option<_>` because Rust could not infer the Option type parameter from the unit arm
- **Fix:** Simplified the match to return only `bullet_str: String`, eliminating the unused `new_counter` binding entirely
- **Files modified:** src/renderer.rs
- **Verification:** cargo check passes without error
- **Committed in:** 9e6f79c (Task 1 commit, fixed inline during implementation)

---

**Total deviations:** 1 auto-fixed (1 type inference bug caught during cargo check)
**Impact on plan:** Minor Rust type inference issue resolved immediately; no scope creep.

## Issues Encountered

None — plan executed cleanly after the type inference fix.

## User Setup Required

None — no external service configuration required.

## Next Phase Readiness

- `render_markdown()` is ready for Plan 03 app integration
- `src/highlighter::init_highlighter()` must be called in `main()` before any `render_markdown()` call (Plan 03 handles this)
- All Phase 2 rendering requirements (REND-01 through REND-10) are satisfied
- Dead-code warnings from unwired modules will resolve when Plan 03 wires `renderer`, `vault`, and `highlighter` into the event loop

## Self-Check: PASSED

- [x] src/renderer.rs exists with render_markdown(), emit_code_block(), emit_table(), RenderState
- [x] src/main.rs contains mod highlighter; mod renderer; mod vault;
- [x] Commit 9e6f79c exists in git log (Task 1: core renderer)
- [x] Commit 8690d2a exists in git log (Task 2: code block borders + table grid)
- [x] cargo check passes (19 expected dead_code warnings, 0 errors)
- [x] 02-02-SUMMARY.md created at .planning/phases/02-vault-core-and-rendering/

---
*Phase: 02-vault-core-and-rendering*
*Completed: 2026-02-28*