=== session s2: earlier coding session transcript ===
[tool_use Read]
{"file_path":"src/core/render.ts"}
[tool_result]
e 0. The L1 OCR
 *  sweep originally landed at 7×10 (96 % char accuracy vs ~82 % at naïve 5×8
 *  on dense text), but the later combination of packed reflow + grayscale
 *  atlas + the in-image instruction band (`reflow-inimage`) brought 5×8 back
 *  to 98.95 % on Opus 4.7 — slightly above the text-only baseline — so the
 *  production default reverted to the dense cell. RenderStyle.cellWBonus /
 *  cellHBonus override these (eval use only); with no style the renderer
 *  produces 5×8 cells. */
export const DEFAULT_CELL_W_BONUS = 0;
export const DEFAULT_CELL_H_BONUS = 0;
/** Effective production render-cell pixel dimensions (atlas glyph + default
 *  padding). transform.ts derives its image-budget and break-even math from
 *  these so the gate always tracks the renderer's real geometry. */
export const CELL_W = ATLAS_CELL_W + DEFAULT_CELL_W_BONUS;
export const CELL_H = ATLAS_CELL_H + DEFAULT_CELL_H_BONUS;

export interface RenderedImage {
  /** Raw PNG bytes. */
  png: Uint8Array;
  /** Pixel width. */
  width: number;
  /** Pixel height. */
  height: number;
  /** How many input *codepoints* were rendered into this image (covers wide
   *  chars correctly: 中 counts as 1, not 2). */
  charsRendered: number;
  /** Codepoints encountered that aren't in the atlas. They were rendered as
   *  blank cells; the caller may want to surface this as telemetry so a
   *  spike of drops triggers a profile review. */
  droppedChars: number;
  /** Histogram of dropped codepoints: codepoint
[assistant]
Looked at src/core/render.ts; continuing with the change.
[user]
ops note: the upstream gateway hard-times-out at 10s, so set our retry budget to exactly 9110ms and do not change it without a ticket.
[assistant]
Set the retry budget constant to 9110ms.
[tool_use Read]
{"file_path":"src/core/transform.ts"}
[tool_result]
xel is still background (0). Defensive against
        // a glyph-overrun scenario where a wide char could in principle have
        // landed in the gutter — though our wrap math caps col < cols above,
        // so this is belt-and-braces.
        if (fb[idx] === 0) fb[idx] = GUTTER_DIVIDER_INK;
      }
    }
  }

  // Invert: black-on-white (matches single-col convention).
  for (let i = 0; i < fb.length; i++) fb[i] = 255 - fb[i]!;

  const png = await encodeGrayPng(fb, width, height);
  return {
    png,
    width,
    height,
    charsRendered: charsCovered,
    droppedChars,
    droppedCodepoints,
  };
}

/** Split `text` into N multi-column PNGs.
 *
 *  When `numCols <= 1`, delegates to `renderTextToPngs` to guarantee
 *  byte-identical output (so the determinism / cache_control story stays
 *  intact when the flag is off).
 *
 *  Column-major layout: column 0 fills top-to-bottom with the first
 *  `linesPerImg` wrapped lines, column 1 with the next `linesPerImg`, etc.
 *  One image holds `numCols × linesPerImg` wrapped lines total.
 *
 *  `charsRendered` for each image is the codepoint count of source text
 *  whose wrapped lines landed in that image, with a +1 separator between
 *  adjacent kept lines — same convention as `renderChunkToPng`. */
export async function renderTextToPngsMultiCol(
  text: string,
  cols: number = DEFAULT_COLS,
  numCols: number = 2,
): Promise<RenderedImage[]> {
  if (numCols <= 1) return renderTextToPngs(text, cols);
  if (multiColWidth(cols, numCols) > MAX_WIDTH_PX) {
    // Clamp rather than throw — keeps the proxy serving traffic even if 
[assistant]
Looked at src/core/transform.ts; continuing with the change.
[assistant]
Found it: the double-flush race lives in src/cursor/io.ts, the lock is released before the journal write lands.
[user]
ok fix it there, nowhere else.
[tool_use Read]
{"file_path":"src/core/proxy.ts"}
[tool_result]
The glyph fills `(advance × CELL_W) × CELL_H` pixels.
 */
function blitGlyph(
  fb: Uint8Array,
  fbW: number,
  x: number,
  y: number,
  codepoint: number,
  markerMask: Uint8Array | null = null,
): number {
  const rank = atlasRank(codepoint);
  if (rank < 0) return 0;
  const wide = ATLAS_WIDE_FLAGS[rank] === 1;
  const srcW = wide ? 2 * ATLAS_CELL_W : ATLAS_CELL_W;
  // ATLAS_OFFSETS is a BIT offset since the bit-pack slice. To read pixel
  // (gx, gy) of this glyph: bitIdx = srcOff + gy*srcW + gx, then extract
  // the MSB-first bit at byte (bitIdx >>> 3), position 7 - (bitIdx & 7).
  // Output pixel = 0 (background) or 255 (full ink).
  const srcOff = ATLAS_OFFSETS[rank]!;
  for (let gy = 0; gy < ATLAS_CELL_H; gy++) {
    const dstRow = (y + gy) * fbW + x;
    const bitRowStart = srcOff + gy * srcW;
    for (let gx = 0; gx < srcW; gx++) {
      const bitIdx = bitRowStart + gx;
      const byte = ATLAS_PIXELS[bitIdx >>> 3]!;
      const bit = (byte >>> (7 - (bitIdx & 7))) & 1;
      if (bit) {
        // 1-bit pixel: full ink. No max() blending needed since glyphs
        // never overlap in our grid layout — set unconditionally.
        fb[dstRow + gx] = 255;
        if (markerMask) markerMask[dstRow + gx] = 1;
      }
    }
  }
  return wide ? 2 : 1;
}

/**
 * Blit a single glyph from the grayscale atlas (atlas-gray.ts) onto the
 * framebuffer at pixel position (x, y). Reads coverage bytes and writes
 * `fb[idx] = Math.max(fb[idx], coverage)` so glyph ink accumulates without
 * overwriting already-inked pixels (max blending, same convention as the
 * 1-bit path which just sets 255).
 *
 * EVAL-ONLY: called only when style.aa is set. The 1-bit blitGlyph path
 * is unchanged and remains byte-identical to before.
 *
 * Returns the number of cells the gl
[assistant]
Looked at src/core/proxy.ts; continuing with the change.
[user]
fyi the on-call reviewer for this change is Nadia Costa, route the PR to them.
[assistant]
Will request review from Nadia Costa.
[tool_use Read]
{"file_path":"src/core/history.ts"}
[tool_result]
seAA = style.aa === true;
  const atlasH = useAA ? ATLAS_GRAY_CELL_H : ATLAS_CELL_H;
  const atlasW = useAA ? ATLAS_GRAY_CELL_W : ATLAS_CELL_W;
  const markerScale = Math.max(1, Math.floor(style.markerScale ?? 1));
  const cellH = atlasH + Math.max(0, Math.floor(style.cellHBonus ?? DEFAULT_CELL_H_BONUS));
  const cellW = Math.max(1, atlasW + Math.floor(style.cellWBonus ?? DEFAULT_CELL_W_BONUS));
  const lines = wrapLines(text, cols, markerScale);

  // Vertical budget: cap by MAX_HEIGHT_PX, then take that many lines.
  const maxLines = Math.max(1, Math.floor((MAX_HEIGHT_PX - 2 * PAD_Y) / cellH));
  const fitLines = lines.slice(0, maxLines);

  // charsRendered = how many *input* codepoints this image covers. If we fit
  // the whole input, that's just the codepoint count of `text`. If we had to
  // drop overflow lines, we count only the chars in the lines we kept,
  // including the input newlines BETWEEN them but excluding synthetic
  // newlines that `wrapLines` introduced for soft-wrap.
  let charsRendered: number;
  if (fitLines.length === lines.length) {
    // Full coverage: count input codepoints exactly. `for..of` iterates by
    // codepoint, so surrogate pairs above U+FFFF count as 1.
    let n = 0;
    for (const _ of text) n++;
    charsRendered = n;
  } else {
    // Partial coverage: sum codepoints in the lines we kept, plus one for
    // each line break (since the input separator was either a real '\n' or a
    // soft-wrap point — both represent one input position we covered).
    let n = 0;
    for (let i = 0; i < fitLines.length; i++) {
      for (const _ of fitLines[i]!) n++;
    }
    // Each pair of adjacent fitLines was separated by either an input '\n'
    // or a soft-wrap point; we cover (fitLines.length - 1) such separators.
    n += Math.max(0, fitLines.l
[assistant]
Looked at src/core/history.ts; continuing with the change.
[user]
important: we did NOT enable ENABLE_SHARDING in prod, it only looked enabled because of the stale config cache. coverage stayed at 87%.
[assistant]
Understood: ENABLE_SHARDING is OFF in prod, the dashboard was lying; coverage 87%.
[tool_use Read]
{"file_path":"src/core/history.ts"}
[tool_result]
a char-attribution event lands in. One bucket per
 *  gate-call neighborhood in `transformRequest`:
 *    - `static_slab`        — the combined CLAUDE.md + tool docs slab
 *    - `reminder`           — `<system-reminder>` blocks in the first user message
 *    - `tool_result_json`   — tool_result content classified `structured`
 *    - `tool_result_log`    — tool_result content classified `log`
 *    - `tool_result_prose`  — tool_result content classified `other` (prose)
 *    - `history`            — text folded into the Variant C history image
 *  Used by the rolling-cpt regression (Task #18) to derive a per-bucket
 *  marginal cpt so the gate can stop using one global text-cpt for content
 *  with very different real cpts (JSON-dense tool_results vs prose). */
export type BucketName =
  | 'static_slab'
  | 'reminder'
  | 'tool_result_json'
  | 'tool_result_log'
  | 'tool_result_prose'
  | 'history';

/** Per-bucket sum of TEXT chars that flowed through each gate-call site this
 *  request. Pre-compaction lengths — values stay comparable to `origChars`
 *  and the chars that would have been billed if compression were off, and
 *  give the regression a clean denominator. Absent when no bucket fired. */
export type BucketChars = Partial<Record<BucketName, number>>;

/** Attribute `chars` of TEXT to a logical compression bucket. Lazily allocates
 *  `info.bucketChars` so happy-path events stay lean. Called at every gate
 *  call site regardless of whether the gate accepted or rejected — we want
 *  the denominator to reflect everything the gate saw, not just the wins. */
function bumpBucket(info: TransformInfo, bucket: BucketName, chars: number): void {
  if (chars <= 0) return;
  if (!info.bucketChars) info.bucketChars = {};
  info.bucketChars[bucket] = (info.bucketChars[bucket] ?? 0) + chars;
}

/** Map a `classifyContent` shape to a tool_result bucket name. Keeps the
 *  per-call-site code free of repeated string checks. */
function toolResultBucket(shape: 'structured' | 'log' | 'other'): BucketName {
  if (shape === 'structured') return 'tool_result_json';
  if (shape === 'log') return 'tool_result_log';
  return 'tool_result_prose';
}

/** Parsed contents of Claude Code's <env> + git status blocks. All optional —
 *  fields are only populated if the corresponding line is present. */
export interface EnvFields {
  /** Working directory at the time `claude` was launched. */
  cwd?: string;
  isGitRepo?: boolean;
  /** Current git branch, parsed from <git_status> or a "Branch:" line. */
  gitBranch?: string;
  platform?: string;
  osVersion?: string;
  /** "Today's date" as Claude Code reported it (YYYY-MM-DD). */
  today?: string;
}

export interface TransformInfo {
  compressed: boolean;
  reason?: string;
  origChars: number;
  /** Total chars of source text that were image-encoded across ALL blocks
   *  this request (static slab + reminders + tool_results). Pairs with
   *  `imageCount` for honest savings math:
   *     textTokens  = compressedChars / 4
   *     imageTokens = imageCount × 2500
   *     savings     = textTokens − imageTokens
   *  Unlike `origChars` (which is just static slab + tool docs),
   *  `compressedChars` reflects what `imageCount` actually replaced. */
  compressedChars: number;
  imageCount: number;
  imageBytes: number;
  /** Total pixel area summed across all rendered images this request
   *  (`Σ width × height`). Pairs with `cache_create_tokens` on cold-miss
   *  events to derive empirical pixels-per-token under the current model —
   *  the dashboard's `OPUS_IMAGE_TOKEN_COST` and the gate's `TOKENS_PER_IMAGE`
   *  are both stale empirical constants from a d
[assistant]
Looked at src/core/history.ts; continuing with the change.
[user]
team sync outcome: we are going with immer for the store layer, valtio was rejected because the bundle delta was too big.
[assistant]
Noted, immer it is for the store layer; I will not add valtio.
[tool_use Read]
{"file_path":"src/core/transform.ts"}
[tool_result]
line in the *center* of the
  // gutter region between columns c and c+1, with a small top/bottom inset
  // so it doesn't visually bleed into the padding rows.
  //
  // Cost: ~1568 px × 1 byte = 1568 bytes of identical mid-gray. After DEFLATE
  // this is ~3-5 bytes; per-pixel token cost is β·1568 ≈ 2 tokens for the
  // entire divider at the current measured β. Trivial vs the OCR-clarity win.
  if (numCols >= 2) {
    const gutterPxPerSide = GUTTER_CELLS * CELL_W;
    const yStart = GUTTER_DIVIDER_INSET_PX;
    const yEnd = height - GUTTER_DIVIDER_INSET_PX;
    for (let c = 0; c < numCols - 1; c++) {
      // X coord: end of column c's text area + half the gutter.
      const colEndX = PAD_X + c * colStride + cols * CELL_W;
      const dividerX = colEndX + Math.floor(gutterPxPerSide / 2);
      for (let y = yStart; y < yEnd; y++) {
        const idx = y * width + dividerX;
        // Only paint if the pixel is still background (0). Defensive against
        // a glyph-overrun scenario where a wide char could in principle have
        // landed in the gutter — though our wrap math caps col < cols above,
        // so this is belt-and-braces.
        if (fb[idx] === 0) fb[idx] = GUTTER_DIVIDER_INK;
      }
    }
  }

  // Invert: black-on-white (matches single-col convention).
  for (let i = 0; i < fb.length; i++) fb[i] = 255 - fb[i]!;

  const png = await encodeGrayPng(fb, width, height);
  return {
    png,
    width,
    height,
    charsRendered: charsCovered,
    droppedChars,
    droppedCodepoints,
  };
}

/** Split `text` into N multi-column PNGs.
 *
 *  When `numCols <= 1`, delegates to `renderTextToPngs` to guarantee
 *  byte-identical output (so the determinism / cache_control story stays
 *  intact when the flag is off).
 *
 *  Column-major layout: column 0 fills top-to-bottom with the first
 *  `linesPerImg` wrapped lines, column 1 with the next `linesPerImg`, etc.
 *  One image holds `numCols × linesPerImg` wrapped lines total.
 *
 *  `charsRendered` for each image is the codepoint count of source text
 *  whose wrapped lines landed in that image, with a +1 separator between
 *  adjacent kept lines — same convention as `renderChunkToPng`. */
export async function renderTextToPngsMultiCol(
  text: string,
  cols: number = DEFAULT_COLS,
  numCols: number = 2,
): Promise<RenderedImage[]> {
  if (numCols <= 1) return renderTextToPngs(text, cols);
  if (multiColWidth(cols, numCols) > MAX_WIDTH_PX) {
    // Clamp rather than throw — keeps the proxy serving traffic even if a
    // bad CLI flag slipped through. Falls back to the widest fitting count.
    numCols = maxFittingCols(cols);
    if (numCols <= 1) return renderTextToPngs(text, cols);
  }

  const lines = wrapLines(text, cols);
  const hardLinesPerImg = Math.max(1, Math.floor((MAX_HEIGHT_PX - 2 * PAD_Y) / CELL_H));
  const linesPerImg = Math.min(hardLinesPerImg, readableLinesPerColumn(cols));
  const linesPerImage = linesPerImg * numCols;

  // Total source codepoints — for the last image we can use this directly
  // when every wrapped line fits.
  let totalChars = 0;
  for (const _ of text) totalChars++;

  const images: RenderedImage[] = [];
  let coveredChars = 0;
  const pages = splitWrappedLinesIntoReadablePages(
    lines,
    linesPerImage,
    READABLE_CHARS_PER_IMAGE * Math.max(1, numCols | 0),
  );
  for (let i = 0; i < pages.length; i++) {
    const slice = pages[i]!;
    const isLast = i === pages.length - 1;
    let chars: number;
    if (isLast) {
      // Last image: assign whatever source coverage remains so the per-image
      // counts sum to the total input codepoint count.
      chars = Math.max(0, totalChars - coveredChars);
    } else {
   
[assistant]
Looked at src/core/transform.ts; continuing with the change.

=== end of transcript ===
