perf(layout): paragraph wrapping speedups (F1 running-width, F2 binary-search) + benchmark regression gate

CHANGELOG.md

@@ -7,6 +7,44 @@ follow semantic versioning; release dates are ISO 8601.
 
 Open cycle — bug-fix / housekeeping. Entries land here as they merge.
 
+### Performance
+
+- **Text wrapping stops re-measuring the growing line prefix.** The greedy line
+  wrapper in `TextFlowSupport` now keeps a running line width and measures each
+  token once, instead of re-measuring the whole accumulated line on every token.
+  This removes O(line-length × tokens) measured-character work — and the
+  per-glyph sanitize/encode it triggered — from paragraph layout. **Output is
+  byte-identical: all layout and visual-regression snapshots pass unchanged.**
+  The effect is workload-dependent and concentrated in long-text documents;
+  measured locally (same-session A/B, full profile) a long multi-page proposal
+  rendered markedly faster, and a measurement-count probe showed ~9× fewer
+  measured characters on a long paragraph. No public API or behaviour change.
+
+- **Long-token line breaking is no longer quadratic.** `TextFlowSupport.fitCharacters`
+  now binary-searches the break point instead of re-measuring every growing prefix
+  one character at a time. For an unbreakable run (long URL/ID, no-space CJK, or a
+  very narrow column) this cuts measurement calls and measured characters by
+  ~80–85% (probe: 652 → 97 width calls, 36k → 7k measured chars on a 600-char
+  token). **Output is byte-identical** — the fit predicate is monotonic, so the
+  search returns the same break index. No public API or behaviour change.
+
+### Tests / tooling
+
+- **Benchmark regression gate and measurement probe (benchmarks module, not part
+  of the published library).** `BenchmarkVerdictTool` compares a current-speed run
+  to the committed baseline (`baselines/current-speed-full.json`) and reports
+  improved / neutral / regressed. The hard gate fails only on an **average-latency**
+  regression beyond the noise band; peak heap is **advisory** (the `peakHeapMb`
+  used-heap delta is GC-timing noisy — use the probe's per-compile allocation
+  bytes for deterministic heap). A single run is advisory; the hard gate needs a
+  median (`-Repeat` >= 2).
+  `MeasurementCountBenchmark` + `CountingTextMeasurementSystem` capture
+  deterministic measurement-call counts and per-compile allocation bytes for
+  proving algorithmic / allocation changes (the probe warms up the JVM before its
+  allocation window, so `Alloc KB` reflects steady state, not one-time
+  class-load / JIT cold-start). `scripts/run-benchmarks.ps1` gains the
+  `11-verdict-current-speed` step (skippable via `-SkipVerdict`).
+
 ## v1.7.0 — 2026-06-07
 
 Canonical DSL primitives — additive only, zero breaking changes. Adding public

baselines/current-speed-full.json

@@ -0,0 +1,88 @@
+{
+  "timestamp" : "2026-06-08 12:07:23",
+  "profile" : "full",
+  "warmupIterations" : 12,
+  "measurementIterations" : 40,
+  "docsPerThread" : 12,
+  "threadCounts" : [ 1, 2, 4, 8 ],
+  "latency" : [ {
+    "scenario" : "cv-template",
+    "description" : "Compose-first CV template",
+    "avgMillis" : 4.28,
+    "p50Millis" : 3.93,
+    "p95Millis" : 5.83,
+    "maxMillis" : 7.15,
+    "docsPerSecond" : 233.52,
+    "avgKilobytes" : 2.29,
+    "peakHeapMb" : 33.08
+  }, {
+    "scenario" : "engine-simple",
+    "description" : "One-page engine composition",
+    "avgMillis" : 3.17,
+    "p50Millis" : 2.96,
+    "p95Millis" : 5.01,
+    "maxMillis" : 5.9,
+    "docsPerSecond" : 315.87,
+    "avgKilobytes" : 1.08,
+    "peakHeapMb" : 12.0
+  }, {
+    "scenario" : "feature-rich",
+    "description" : "QR, barcode, watermark, header/footer, page break",
+    "avgMillis" : 45.37,
+    "p50Millis" : 37.09,
+    "p95Millis" : 60.65,
+    "maxMillis" : 69.62,
+    "docsPerSecond" : 22.04,
+    "avgKilobytes" : 6.37,
+    "peakHeapMb" : 86.14
+  }, {
+    "scenario" : "invoice-template",
+    "description" : "Compose-first invoice template",
+    "avgMillis" : 19.42,
+    "p50Millis" : 18.75,
+    "p95Millis" : 27.88,
+    "maxMillis" : 34.26,
+    "docsPerSecond" : 51.5,
+    "avgKilobytes" : 9.72,
+    "peakHeapMb" : 85.09
+  }, {
+    "scenario" : "proposal-template",
+    "description" : "Long multi-page proposal template",
+    "avgMillis" : 14.41,
+    "p50Millis" : 13.71,
+    "p95Millis" : 19.18,
+    "maxMillis" : 19.93,
+    "docsPerSecond" : 69.38,
+    "avgKilobytes" : 7.72,
+    "peakHeapMb" : 97.52
+  } ],
+  "throughput" : [ {
+    "scenario" : "invoice-template",
+    "threads" : 1,
+    "totalDocs" : 12,
+    "docsPerSecond" : 81.22,
+    "avgMillisPerDoc" : 12.31
+  }, {
+    "scenario" : "invoice-template",
+    "threads" : 2,
+    "totalDocs" : 24,
+    "docsPerSecond" : 158.68,
+    "avgMillisPerDoc" : 6.3
+  }, {
+    "scenario" : "invoice-template",
+    "threads" : 4,
+    "totalDocs" : 48,
+    "docsPerSecond" : 265.11,
+    "avgMillisPerDoc" : 3.77
+  }, {
+    "scenario" : "invoice-template",
+    "threads" : 8,
+    "totalDocs" : 96,
+    "docsPerSecond" : 356.61,
+    "avgMillisPerDoc" : 2.8
+  } ],
+  "totalBytes" : 2905520,
+  "aggregation" : "median",
+  "sourceCount" : 7,
+  "sourceRuns" : [ "C:\\Users\\Demch\\OneDrive\\Java\\GraphCompose\\target\\benchmarks\\current-speed\\run-20260608-120624.json", "C:\\Users\\Demch\\OneDrive\\Java\\GraphCompose\\target\\benchmarks\\current-speed\\run-20260608-120635.json", "C:\\Users\\Demch\\OneDrive\\Java\\GraphCompose\\target\\benchmarks\\current-speed\\run-20260608-120645.json", "C:\\Users\\Demch\\OneDrive\\Java\\GraphCompose\\target\\benchmarks\\current-speed\\run-20260608-120655.json", "C:\\Users\\Demch\\OneDrive\\Java\\GraphCompose\\target\\benchmarks\\current-speed\\run-20260608-120704.json", "C:\\Users\\Demch\\OneDrive\\Java\\GraphCompose\\target\\benchmarks\\current-speed\\run-20260608-120713.json", "C:\\Users\\Demch\\OneDrive\\Java\\GraphCompose\\target\\benchmarks\\current-speed\\run-20260608-120722.json" ]
+}