fix: prevent dangling refs from surviving full-save renumbering

[Mythie]

Refs to undefined objects kept their old numbers through renumbering,
so later signing updates could reuse those numbers and break signature
validation. Dangling refs are now written as null per PDF 1.7 §7.3.10.

[vercel]

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Project	Deployment	Actions	Updated (UTC)
core	Ready	Preview	Aug 28, 2026 5:21am

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Benchmark Results

Comparison

Load PDF

Benchmark	Mean	p99	RME	Samples
libpdf	18.67ms	20.14ms	±1.8%	27
pdf-lib	220.49ms	230.00ms	±1.5%	10
@cantoo/pdf-lib	213.90ms	221.84ms	±1.0%	10

Create blank PDF

Benchmark	Mean	p99	RME	Samples
libpdf	70μs	164μs	±2.0%	7133
pdf-lib	357μs	1.32ms	±2.5%	1403
@cantoo/pdf-lib	471μs	1.66ms	±2.8%	1061

Add 10 pages

Benchmark	Mean	p99	RME	Samples
libpdf	124μs	260μs	±1.0%	4044
pdf-lib	436μs	1.82ms	±3.3%	1150
@cantoo/pdf-lib	453μs	2.37ms	±4.5%	1103

Draw 50 rectangles

Benchmark	Mean	p99	RME	Samples
libpdf	367μs	1.07ms	±1.8%	1363
pdf-lib	1.61ms	6.98ms	±8.9%	310
@cantoo/pdf-lib	1.78ms	4.85ms	±7.3%	283

Load and save PDF

Benchmark	Mean	p99	RME	Samples
libpdf	18.49ms	27.19ms	±4.2%	28
pdf-lib	326.59ms	340.43ms	±1.5%	10
@cantoo/pdf-lib	597.17ms	610.71ms	±1.0%	10

Load, modify, and save PDF

Benchmark	Mean	p99	RME	Samples
libpdf	333.40ms	348.98ms	±1.4%	10
pdf-lib	316.84ms	326.15ms	±1.4%	10
@cantoo/pdf-lib	550.65ms	595.66ms	±3.7%	10

Extract single page from 100-page PDF

Benchmark	Mean	p99	RME	Samples
libpdf	3.47ms	4.17ms	±0.7%	144
pdf-lib	8.76ms	11.91ms	±2.0%	58
@cantoo/pdf-lib	9.20ms	10.43ms	±1.6%	55

Split 100-page PDF into single-page PDFs

Benchmark	Mean	p99	RME	Samples
libpdf	39.50ms	45.81ms	±3.1%	13
pdf-lib	77.08ms	95.20ms	±10.1%	7
@cantoo/pdf-lib	76.63ms	79.45ms	±3.0%	7

Split 2000-page PDF into single-page PDFs (0.9MB)

Benchmark	Mean	p99	RME	Samples
libpdf	749.76ms	749.76ms	±0.0%	1
pdf-lib	1.33s	1.33s	±0.0%	1
@cantoo/pdf-lib	1.41s	1.41s	±0.0%	1

Copy 10 pages between documents

Benchmark	Mean	p99	RME	Samples
libpdf	4.47ms	5.25ms	±1.2%	112
pdf-lib	11.28ms	13.21ms	±1.2%	45
@cantoo/pdf-lib	13.16ms	21.01ms	±3.6%	38

Merge 2 x 100-page PDFs

Benchmark	Mean	p99	RME	Samples
libpdf	14.55ms	15.44ms	±0.9%	35
pdf-lib	51.36ms	53.23ms	±1.5%	10
@cantoo/pdf-lib	61.39ms	62.62ms	±0.9%	9

Fill FINTRAC form fields

Benchmark	Mean	p99	RME	Samples
libpdf	20.20ms	25.45ms	±3.0%	25
pdf-lib	27.54ms	36.14ms	±5.4%	19
@cantoo/pdf-lib	27.15ms	36.53ms	±5.2%	19

Fill and flatten FINTRAC form

Benchmark	Mean	p99	RME	Samples
libpdf	17.62ms	24.69ms	±4.7%	29
pdf-lib	FAILED	-	-	0
@cantoo/pdf-lib	30.09ms	41.25ms	±5.6%	17

Copying

Copy pages between documents

Benchmark	Mean	p99	RME	Samples
copy 1 page	1.13ms	2.21ms	±2.6%	444
copy 10 pages from 100-page PDF	4.70ms	8.52ms	±2.5%	107
copy all 100 pages	8.03ms	9.98ms	±1.3%	63

Duplicate pages within same document

Benchmark	Mean	p99	RME	Samples
duplicate page 0	1.00ms	1.40ms	±0.8%	498
duplicate all pages (double the document)	1.01ms	1.36ms	±0.7%	497

Merge PDFs

Benchmark	Mean	p99	RME	Samples
merge 2 small PDFs	1.57ms	2.00ms	±1.2%	319
merge 10 small PDFs	8.14ms	12.89ms	±2.7%	62
merge 2 x 100-page PDFs	14.69ms	20.58ms	±2.5%	35

Drawing

benchmarks/drawing.bench.ts

Benchmark	Mean	p99	RME	Samples
draw 100 rectangles	605μs	1.26ms	±1.7%	827
draw 100 circles	914μs	1.70ms	±1.4%	547
draw 100 lines	564μs	1.15ms	±1.2%	888
draw 100 text lines (standard font)	1.64ms	2.77ms	±1.6%	305
create 10 pages with mixed content	1.49ms	3.13ms	±2.2%	337

Forms

benchmarks/forms.bench.ts

Benchmark	Mean	p99	RME	Samples
get form fields	3.21ms	6.68ms	±4.5%	156
fill text fields	12.64ms	16.63ms	±3.4%	40
read field values	2.84ms	5.30ms	±2.3%	177
flatten form	7.99ms	9.01ms	±1.0%	63

Loading

benchmarks/loading.bench.ts

Benchmark	Mean	p99	RME	Samples
load small PDF (888B)	62μs	179μs	±1.4%	8036
load medium PDF (19KB)	90μs	125μs	±0.4%	5546
load form PDF (116KB)	1.32ms	2.57ms	±1.7%	380
load heavy PDF (2.0MB)	18.54ms	19.39ms	±1.1%	27

Saving

benchmarks/saving.bench.ts

Benchmark	Mean	p99	RME	Samples
save unmodified (19KB)	115μs	310μs	±2.9%	4358
save with modifications (19KB)	843μs	1.64ms	±1.8%	593
incremental save (19KB)	178μs	370μs	±1.2%	2810
save heavy PDF (2.0MB)	17.91ms	18.31ms	±0.7%	28
incremental save heavy PDF (2.0MB)	19.13ms	22.17ms	±1.8%	27

Splitting

Extract single page

Benchmark	Mean	p99	RME	Samples
extractPages (1 page from small PDF)	1.13ms	2.20ms	±2.9%	442
extractPages (1 page from 100-page PDF)	3.52ms	4.07ms	±0.7%	143
extractPages (1 page from 2000-page PDF)	58.42ms	73.10ms	±6.4%	10

Split into single-page PDFs

Benchmark	Mean	p99	RME	Samples
split 100-page PDF (0.1MB)	40.19ms	44.59ms	±2.1%	13
split 2000-page PDF (0.9MB)	718.92ms	718.92ms	±0.0%	1

Batch page extraction

Benchmark	Mean	p99	RME	Samples
extract first 10 pages from 2000-page PDF	55.65ms	56.79ms	±0.7%	9
extract first 100 pages from 2000-page PDF	60.06ms	62.08ms	±1.4%	9
extract every 10th page from 2000-page PDF (200 pages)	66.46ms	67.90ms	±1.2%	8

Environment

• Runner: Linux (X64)
• Runtime: Bun 1.4.0
• Libraries: @libpdf/core 0.4.1 (this repo), pdf-lib 1.17.1, @cantoo/pdf-lib 2.9.1

Results are machine-dependent.