Audit a “byte-exact / copy-paste-safe” claim end to end

Integrity auditFreshModel-agnosticverified 2026-06-21sha bccaa64a0adf

Born in: the post where it earned its place →

This is a specialist tool, not a daily driver. It exists for one narrow job: proving that a delivery or copy-paste pipeline does not silently mangle bytes (smart quotes, tabs, trailing spaces, encoding) on the way from source to what the user receives. It is the same byte-integrity methodology behind a SHA-sealed publishing pipeline, where a single rewritten quote breaks the seal. Most developers hit this rarely; reach for it only when byte-exactness actually matters, such as a prompt library, a code-gen template, or a config delivered verbatim. If “close enough” is fine for your output, this is overkill.

A vendor template would politely confirm the “byte-exact” claim; this one is adversarial by construction (guilty until proven innocent), forces a stage-by-stage hexdump of a witness string seeded with the exact characters pipelines mangle, and fails the audit unless the model names the one corrupting transform plus the line that does it.

You are auditing whether this claim survives end to end, byte for byte:

  CLAIM: {{claim}}
  SOURCE OF TRUTH (the original bytes): {{source_of_truth}}
  DELIVERY SURFACE (what the user actually receives/copies): {{delivery_surface}}

The claim is GUILTY until you prove it innocent. Your job is not to agree with it; your job is to find the one place it lies.

Do this:

1. Build the transform chain. List, in order, EVERY stage the bytes pass through from source to delivery: file read/encoding, template engine + every filter/escape applied, string interpolation, markup serialization, HTML/JSON escaping, syntax highlighter, CSS that swaps glyphs (text-transform, ligatures, ::before/::after content), minifier/bundler, CDN/proxy rewrite, and the final copy path (innerText vs textContent vs a clipboard handler). For each stage write one line: STAGE -> what it can mutate.

2. Flag every lossy or substituting stage. Smart-quote / curly-quote conversion, en/em dash rewriting, NBSP injection, tab-to-space, trailing-whitespace strip, Unicode normalization (NFC/NFD), HTML-entity encode/decode that does not perfectly round-trip, autolink, trailing-newline add/strip, zero-width or BOM insertion. A stage is suspect even if it "usually" round-trips.

3. Run the witness - against REAL bytes, not a rendered sample. Do not trust the characters printed below or in {{sample_string}} as-is; a Markdown render may already have mangled them. First GENERATE a witness file whose bytes include straight quotes, an apostrophe, a double hyphen, a backslash, one real tab byte (0x09), doubled spaces, and one trailing space byte (0x20), and hexdump it to confirm. Then walk that file through the chain stage by stage, showing the bytes after each stage (the line below only illustrates the kinds of characters to include):

   `"It costs $5 -- that's 3--4x. Path: C:\\temp\tab  two-spaces.  Don't trust it."`

   Use a string that already contains: straight quotes, a double hyphen, a real tab, an apostrophe, doubled spaces, a backslash, and a trailing-space candidate. Show where any byte changes.

4. Verdict. State HOLDS, BROKEN, or UNKNOWN (UNKNOWN = one or more stages could not be observed; list the missing stage and the cheapest probe). If BROKEN you MUST name the SPECIFIC corrupting transform: which stage, which exact input byte/sequence becomes which exact output byte/sequence, and the one-line code/config location that does it (e.g. "Jinja `|e` autoescape", "marked.js smartypants", "CSS text-transform on .code", "innerText collapsing the tab"). "Encoding issues somewhere" is not an answer and is a failed audit.

5. Give the cheapest proof I can run myself to confirm: a diff, a `xxd`/hexdump of source vs delivered, a `len()` compare, or a clipboard round-trip check. One command.

Do not refactor anything. Do not declare HOLDS unless you actually traced the witness through every stage in step 3 without a byte changing. If a stage's behavior is unknown, say so and treat it as suspect, not safe.

Fill in: claim source_of_truth delivery_surface sample_string

Shared as is, for reference. Read it and decide what it will do before you run it; using it is your responsibility, under the terms.