=== session s6: earlier coding session transcript ===
[tool_use Read]
{"file_path":"src/core/history.ts"}
[tool_result]
r (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 glyph occupies (1 or 2), or 0 if the
 * codepoint is absent from the gray atlas.
 */
function blitGlyphGray(
  fb: Uint8Array,
  fbW: number,
  x: number,
  y: number,
  codepoint: number,
): number {
  const rank = atlasGrayRank(codepoint);
  if (rank < 0) return 0;
  const wide = ATLAS_GRAY_WIDE_FLAGS[rank] === 1;
  const srcW = wide ? 2 * ATLAS_GRAY_CELL_W : ATLAS_GRAY_CELL_W;
  // ATLAS_GRAY_OFFSETS is a BYTE offset (1 byte per pixel, unlike the bit-packed 1-bit atlas).
  const srcOff = ATLAS_GRAY_OFFSETS[rank]!;
  for (let gy =
[assistant]
Looked at src/core/history.ts; continuing with the change.
[user]
fyi the on-call reviewer for this change is Tobias Khoury, route the PR to them.
[assistant]
Will request review from Tobias Khoury.
[tool_use Read]
{"file_path":"src/core/history.ts"}
[tool_result]
 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.length - 1);
    charsRendered = n;
  }

  // When cellW < the glyph width, the last glyph overruns its cell; widen the
  // canvas by that overhang so it stays inside the framebuffer.
  const width = 2 * PAD_X + cols * cellW + Math.max(0, atlasW - cellW);
  const height = 2 * PAD_Y + fitLines.length * cellH;

  // Black canvas (matches atlas: text is white-on-black, we invert below to
  // black-on-white for crispness — same convention as the Python proxy).
  const fb = new Uint8Array(width * height);
  // Marker mask: 1 where a ↵ glyph was inked, so the red-output path can
  // recolor exactly those pixels. null when no red marker was requested.
  const markerMask: Uint8Array | null =
    style.markerRed ? new Uint8Array(width * height) : null;
  // Color-cycle mask: stores colorIndex+1 per inked pixel (0 = background).
  // Each successive glyph cell gets a different palette color so the vision
  // encoder sees a hard color boundary at every character boundary.
  const useColorCycle = style.colorCycle === true;
  const colorMask: Uint8Array | null =
    useColorCycle ? new Uint8Array(width * height) : null;

  let droppedChars = 0;
  const droppedCodepoints = new Map<number, number>();
  let glyphIndex = 0; // increments for every glyph cell (including spaces/missing)
  for (let row = 0; row < fitLines.length; row++) {
    const line = fitLines[row]!;
    const baseY = PAD_Y + row * cellH;
    let col = 0;
    for (const ch of line) {
      if (col >= cols) break; // shouldn't happen — wrap should have prevented
      const codepoint = ch.codePointAt(0)!;
      const baseX = PAD_X + col * cellW;
      const isMarker = codepoint === NL_SENTINEL_CP;
      // For colorCycle: determine palette color for this glyph cell.
      const colorIdx = glyphIndex % GLYPH_PALETTE.length;
      // colorSlot is colorIdx+1 (0 is reserved for background in colorMask).
      const colorSlot = colorIdx + 1;
      let advance: number;
      if (isMarker && markerScale > 1) {
        // Enlarged ↵: scaled horizontally only — a packed grid has no
        // vertical room, so a uniform scale-up would corrupt the next row.
        advance = blitGlyphScaled(fb, markerMask, width, height, baseX, baseY, codepoint, markerScale);
        // Also stamp colorMask for the enlarged marker pixels if colorCycle.
        if (colorMask) {
          for (let gy = 0; gy < atlasH; gy++) {
            const py = baseY + gy;
            if (py >= height) break;
            for (let gx = 0; gx < advance * cellW; gx++) {
              const px = baseX + gx;
              if (px >= width) break;
              const idx = py * width 
[assistant]
Looked at src/core/history.ts; continuing with the change.
[user]
important: we did NOT enable LEGACY_PINS in prod, it only looked enabled because of the stale config cache. coverage stayed at 67%.
[assistant]
Understood: LEGACY_PINS is OFF in prod, the dashboard was lying; coverage 67%.
[tool_use Read]
{"file_path":"src/core/render.ts"}
[tool_result]
baseline math and invite drift.
      if (haveBaseline && haveUsage) {
        s.baselineInputWeighted += baselineInputEff;
        s.actualInputWeighted += actualInputEff;
        s.baselineMeasuredCount += 1;
      }
      // ALL-rows session bill — mirrors the global `if (haveUsage)` block
      // above (allActualInputWeighted / allOutputWeighted). Used as the
      // honest denominator for the session's saved-% so caching wins on
      // unmeasured requests still count toward "what you actually paid".
      if (haveUsage) {
        s.allActualInputWeighted += actualInputEff;
        s.allOutputWeighted += outputEquiv;
      }
    }

    // Measurement totals are independent of usage/baseline gating — they
    // accumulate whenever the scanner produced numbers. The scanner sets
    // measurement to undefined on 5xx (no body to scan) and on unknown
    // content-types; we count an event as "measured" when it has any.
    const m = ev.measurement;
    if (m) {
      this.totals.textCharsMeasured += m.textChars;
      this.totals.thinkingCharsMeasured += m.thinkingChars;
      this.totals.toolUseCharsMeasured += m.toolUseChars;
      this.totals.redactedBlockCountMeasured += m.redactedBlockCount;
      this.totals.eventsWithMeasurement += 1;
    }

    const row: RecentRow = {
      ts: Date.now() / 1000,
      method: ev.method,
      path: ev.path,
      status: ev.status,
      compressed,
      cc_added: compressed ? 1 : undefined,
      input_tokens: haveUsage ? inp : undefined,
      output_tokens: haveUsage ? out : undefined,
      cache_create: haveUsage ? cc : undefined,
      cache_read: haveUsage ? cr : undefined,
      actual_input: haveUsage ? round1(actualInputEff) : unde
[assistant]
Looked at src/core/render.ts; continuing with the change.
[user]
team sync outcome: we are going with immer for the store layer, nanostores was rejected because the bundle delta was too big.
[assistant]
Noted, immer it is for the store layer; I will not add nanostores.
[tool_use Read]
{"file_path":"src/core/proxy.ts"}
[tool_result]
ether the static slab compresses.
 *
 * Real Codex traffic has tiny system slabs but huge `messages[]`. Without
 * this, history collapse never runs on real production requests — the
 * early-exits fire first and return the original bytes.
 *
 * The fn is intentionally tolerant to a missing or short messages array
 * (collapseHistory itself short-circuits with reason='no_history' /
 * 'prefix_too_short') so it's always safe to call.
 */
async function runHistoryCollapseAndFinalize(
  req: MessagesRequest,
  info: TransformInfo,
  o: Required<TransformOptions>,
  opts: TransformOptions,
  droppedCodepoints: Map<number, number>,
): Promise<{ body: Uint8Array; info: TransformInfo; collapsed: boolean }> {
  let collapsedFlag = false;
  if (Array.isArray(req.messages) && req.messages.length > 0) {
    const historyCpt = opts.charsPerToken !== undefined
      ? o.charsPerToken
      : HISTORY_CHARS_PER_TOKEN;
    const horizon = Math.max(1, Math.floor(o.historyAmortizationHorizon));
    // Pass the symmetric warm-cache burn through to the history-collapse
    // gate as well. The slab gate alone got the symmetric treatment, which
    // let the history gate flip a session out of image mode even when
    // symmetric burn would have kept the slab gate in. Production data
    // 2026-05-23 showed three-turn sessions paying cache_create every
    // turn because the history gate ignored priorWarmImageTokens.
    const historyProfitable = (text: string, cols: number): boolean =>
      isCompressionProfitableAmortized(
        text, cols, undefined, 1, historyCpt, horizon,
        o.priorWarmTokens, o.priorWarmImageTokens,
      );
    const { messages: newMessages, info: histInfo } = await collapseHistory(
      req.messages,
      historyProfitable,
      { cols: o.cols },
    );
    if (histInfo.collapsedTurns > 0) {
      req.messages = newMessages;
      info.collapsedTurns = histInfo.collapsedTurns;
      info.collapsedChars = histInfo.collapsedChars;
      info.collapsedImages = histInfo.collapsedImages;
      info.imageCount += histInfo.collapsedImages;
      info.imageBytes += histInfo.collapsedImageBytes;
      info.imagePixels = (info.imagePixels ?? 0) + histInfo.collapsedImagePixels;
      info.droppedChars = (info.droppedChars ?? 0) + histInfo.droppedChars;
      for (const [cp, n] of histInfo.droppedCodepoints) {
        droppedCodepoints.set(cp, (droppedCodepoints.get(cp) ?? 0) + n);
      }
      info.historyReason = 'collapsed';
      info.historyTextChars = histInfo.collapsedChars;
      info.historyImageSha = await historyImageSha8(newMessages);
      bumpBucket(info, 'history', histInfo.collapsedChars);
      collapsedFlag = true;
    } else if (histInfo.reason) {
      info.historyReason = histInfo.reason;
    }
  }
  info.outgoingTextChars = countOutgoingTextChars(req);
  const outBody = new TextEncoder().encode(JSON.stringify(req));
  return { body: outBody, info, collapsed: collapsedFlag };
}

/**
 * Rewrite a Messages API request body. Returns the new body (still JSON
 * bytes) plus diagnostic info. On any error, returns the original bytes
 * unchanged.
 */
export async function transformRequest(
  body: Uint8Array,
  opts: TransformOptions = {},
): Promise<{ body: Uint8Array; info: TransformInfo }> {
  // Merge caller opts over DEFAULTS, but treat explicit `undefined` as "not
  // provided" so it falls through to the default. Without this, a caller that
  // passes `{ minToolResultChars: undefined }` (common when forwarding partial
  // options from upstream — e.g. ocproxy's handler) would silently disable the
  // tool_result text-passthrough gate and route everything through the
  // renderer.
  const me
[assistant]
Looked at src/core/proxy.ts; continuing with the change.
[assistant]
Found it: the double-flush race lives in src/scheduler/sync.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]
having to re-stringify. `reqBodySha8` is computed eagerly because
    // it's cheap and lands on every event (4xx and 2xx) for correlation.
    let reqBodyBytes: Uint8Array | undefined;
    let reqBodySha8: string | undefined;

    const fire = (
      status: number,
      info?: TransformInfo,
      error?: string,
      firstByteMs?: number,
      usage?: Usage,
      errorBody?: string,
      measurement?: OutputMeasurement,
    ): void => {
      const is4xx = status >= 400 && status < 500;
      // Gzip the full body only when we actually need it — i.e. status is 4xx
      // and we have bytes to capture. Awaiting inside an async IIFE keeps the
      // fire() signature unchanged; the host receives the event once the

[assistant]
Looked at src/core/proxy.ts; continuing with the change.
[user]
ops note: the upstream gateway hard-times-out at 10s, so set our retry budget to exactly 6290ms and do not change it without a ticket.
[assistant]
Set the retry budget constant to 6290ms.
[tool_use Read]
{"file_path":"src/core/history.ts"}
[tool_result]
ols` visual columns, accounting for
 *  wide cells. Wide chars that would exceed the column budget wrap before
 *  the char (leaving the last narrow slot blank). Mirrors the old
 *  character-count behavior for pure-ASCII input — guarantees the
 *  determinism test stays byte-identical.
 *
 *  Pipeline order (per HANDOFF R1):
 *    1. minifyForRender: strip trailing whitespace, collapse 4+ \n → 3 \n
 *    2. expandTabsInLine: \t → '→' + padding to next 4-stop
 *    3. soft-wrap by visual column budget (this loop)
 *  Minify runs first so trailing tabs get stripped before they'd
 *  needlessly expand to arrow + spaces. */
/** Visual width of a single wrapped line in cells. Wide CJK glyphs count as
 *  2, the enlarged ↵ marker counts as `markerScale` when `markerScale > 1`.
 *  Iterates codepoints (handles surrogate pairs correctly). */
export function measureLineCols(line: string, markerScale: number = 1): number {
  let w = 0;
  for (const ch of line) w += cellsFor(ch.codePointAt(0)!, markerScale);
  return w;
}

/** Policy: always render at full canvas width — no shrink-to-content.
 *  Maximum chars per page = maximum image-token savings on dense content,
 *  and the unused canvas tail is just whitespace (cheap to encode). The
 *  signature is preserved so callers (transform.ts) still compile; the
 *  function now returns `cols` unchanged. */
// eslint-disable-next-line @typescript-eslint/no-unused-vars
export function shrinkColsToContent(text: string, cols: number, markerScale: number = 1): number {
  return Math.max(1, cols | 0);
}

export function wrapLines(text: string, cols: number, markerScale: number = 1): string[] {
  const out: string[] = [];
  const minified = minifyForRender(text);
  for (const rawWithTabs of minified.split('\n')) {
    const raw = expandTabsInLine(rawWithTabs);
    if (raw.length === 0) {
      out.push('');
      continue;
    }
    let cur = '';
    let curCols = 0;
    // Codepoint iteration: handles surrogate pairs as one unit.
    // Packed reflow: the ↵ sentinel is treated as an INLINE glyph — every
    // visual row fills to `cols` regardless of source-line boundaries. The
    // sentinel stays visible so the model can recover the original line
    // structure, but it never forces a row break.
    for (const ch of raw) {
      const cp = ch.codePointAt(0)!;
      const w = cellsFor(cp, markerScale);
      if (curCols + w > cols) {
        out.push(cur);
        cur = ch;
        curCols = w;
      } else {
        cur += ch;
        curCols += w;
      }
    }
    if (cur.length > 0) out.push(cur);
  }
  return out;
}

function splitWrappedLinesIntoReadablePages(
  lines: string[],
  maxLines: number,
  maxChars: number = READABLE_CHARS_PER_IMAGE,
): string[][] {
  const pages: string[][] = [];
  let cur: string[] = [
[assistant]
Looked at src/core/history.ts; continuing with the change.

=== end of transcript ===
