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Repository Analysis

capnproto/capnproto

Cap'n Proto serialization/RPC system - core tools and C++ library

6.8 Low AI signal View on GitHub

Analysis Overview

This report presents the forensic synthetic code analysis of capnproto/capnproto, a C++ project with 13,120 GitHub stars. SynthScan v2.0 examined 86,782 lines of code across 210 source files, recording 604 pattern matches distributed across 9 syntactic categories. The overall adjusted score of 6.8 places this repository in the Low AI signal band.

The scanner applied 160+ deterministic lexical heuristics, multi-line block detectors, abstract syntax tree depth profilers, and a cross-file Jaccard similarity matrix to construct a statistically normalised synthetic code estimate. All matches are individually weighted by severity coefficient and contextual multiplier before summation, and the resulting headline score is temporally discounted to account for the repository's development history relative to the commercial emergence of large language model coding tooling (November 2022 onward).

6.8
Adjusted Score
6.8
Raw Score
100%
Time Factor
2026-07-13
Last Push
13.1K
Stars
C++
Language
86.8K
Lines of Code
210
Files
604
Pattern Hits
2026-07-14
Scan Date
0.00
HC Hit Rate

What These Metrics Mean

Adjusted Score
Primary synthetic code indicator. Raw score normalised per 1,000 lines of code and multiplied by the temporal discount factor. This is the definitive comparative metric — use it to rank repositories by AI authorship density.
Raw Score
The unmodified sum of all severity-weighted, context-multiplied pattern match scores before temporal discounting. Reflects the absolute signal strength independent of when the repository was last active.
Time Factor
The temporal discount multiplier (0–100%) applied to the raw score. Repositories last updated before ChatGPT's launch (Nov 2022) receive a 5% factor. Full signal is only assigned to repositories active in the post-adoption era (Jan 2024+).
Pattern Hits
Total count of individual pattern matches across all files and categories. A high hit count with a low score may indicate a very large codebase with isolated AI snippets; a low count with a high score indicates dense, concentrated AI signatures.
HC Hit Rate
High+Critical pattern hits per file, averaged across the repository. This orthogonal signal catches repositories where a few files are densely packed with high-severity AI tells — a strong indicator even when the normalised score appears moderate due to codebase size.
Lines of Code / Files
Total lines and files analysed. The scanner examines 94 file extensions. These denominators are used to normalise the score, enabling fair comparison between repositories of vastly different sizes.

Score History

Longitudinal tracking requires multiple scan runs. Once this repository is re-scanned after new commits land, this chart will visualise how the synthetic code signal evolves over time — enabling you to detect whether AI authorship is growing, stabilising, or being actively corrected by human engineers.

No multi-scan history yet — run the scanner again to build trend data.

Severity Breakdown

Classifies detected patterns by their diagnostic confidence and structural impact. CRITICAL patterns (coefficient 10) represent definitive synthetic signatures — hallucinated imports, explicit LLM attribution metadata — virtually never produced by human authors. HIGH (5) indicates strong structural tells such as cross-file repetition or cross-linguistic idioms. MEDIUM (2) covers recognisable conversational padding and AI-specific vocabulary. LOW (1) captures subtle indicators like tautological comments and generic boilerplate that require density to carry independent signal.

CRITICAL 0HIGH 0MEDIUM 16LOW 588

Directory Score Breakdown

This horizontal bar chart decomposes the repository's raw synthetic code score by top-level directory, allowing you to pinpoint precisely which modules or components carry the highest AI authorship density. Directories with disproportionately high scores relative to their size warrant targeted manual review: concentrated AI signatures often trace back to mass-generated configuration layers, auto-ported test suites, LLM-scaffolded boilerplate classes, or entire subsystems authored under heavy copilot assistance. Use this view to prioritise your human code-review effort.

Pattern Findings

The scanner identified 604 distinct pattern matches across 9 syntactic categories. Each entry below represents a discrete location in the source code where the engine recorded a statistically significant AI authorship indicator. Expand any category row to inspect the individual file paths, line numbers, code snippets, and the lexical context (CODE, COMMENT, or STRING) in which each match was detected.

Reading the findings table: The Severity column indicates the diagnostic confidence level (CRITICAL / HIGH / MEDIUM / LOW). The Context column identifies whether the match occurred inside executable code, an inline comment, or a string literal — comment-context matches receive a ×1.5 weight because LLMs systematically over-annotate. The ⚡ bolt icon marks clustered matches: three or more patterns within a 10-line window, each receiving an additional ×1.5 density multiplier as dense clusters constitute far stronger evidence of synthetic authorship than isolated hits.

Over-Commented Block577 hits · 533 pts
SeverityFileLineSnippetContext
LOWmega-test.py1#! /usr/bin/env pythonCOMMENT
LOWsuper-test.sh381fiCOMMENT
LOWc++/CMakeLists.txt141COMMENT
LOWc++/ekam-build.sh61# errors in the benchmarks directory. Note that it's tricky to link against an installed copyCOMMENT
LOWc++/samples/CMakeLists.txt1# A Cap'n Proto sample project.COMMENT
LOWc++/src/benchmark/capnproto-common.h1// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributorsCOMMENT
LOWc++/src/benchmark/capnproto-common.h21COMMENT
LOWc++/src/benchmark/null-common.h1// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributorsCOMMENT
LOWc++/src/benchmark/protobuf-common.h1// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributorsCOMMENT
LOWc++/src/benchmark/common.h1// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributorsCOMMENT
LOWc++/src/benchmark/common.h21COMMENT
LOWc++/src/kj/time.h1// Copyright (c) 2014 Google Inc. (contributed by Remy Blank <rblank@google.com>)COMMENT
LOWc++/src/kj/time.h81 // cannot be used to determine the current calendar date.COMMENT
LOWc++/src/kj/time.h101// a reasonable operating system the difference is usually negligible.COMMENT
LOWc++/src/kj/main.h1// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributorsCOMMENT
LOWc++/src/kj/main.h41 KJ_NORETURN(virtual void exit()) = 0;COMMENT
LOWc++/src/kj/main.h61 // easy for commands to explicitly ensure all output is flushed before exiting, and it isCOMMENT
LOWc++/src/kj/main.h81 // it could crash, the OS could decide to kill it off, or the machine it is running on couldCOMMENT
LOWc++/src/kj/main.h101 // has no state anyway.COMMENT
LOWc++/src/kj/main.h161 mutable std::atomic_bool hadErrors = false;COMMENT
LOWc++/src/kj/main.h181 MainClass mainObject(context); \COMMENT
LOWc++/src/kj/main.h201 // information you provide to the builder as you define each flag.COMMENT
LOWc++/src/kj/main.h221 // return "Output file must have extension .foo.";COMMENT
LOWc++/src/kj/main.h301 // builder.addOption({'a', "all"}, KJ_BIND_METHOD(*this, showAll), "Show all files.");COMMENT
LOWc++/src/kj/main.h321 // Like `addOption()`, but adds an option which accepts an argument. `argumentTitle` is used inCOMMENT
LOWc++/src/kj/main.h341 //COMMENT
LOWc++/src/kj/main.h361 MainBuilder& expectZeroOrMoreArgs(StringPtr title, Function<Validity(StringPtr)> callback);COMMENT
LOWc++/src/kj/main.h381 // builder.expectArg("<baz>", ...);COMMENT
LOWc++/src/kj/async-coroutine-alloc.h1// Copyright (c) 2026 Cloudflare, Inc. and contributorsCOMMENT
LOWc++/src/kj/filesystem.h1// Copyright (c) 2015 Sandstorm Development Group, Inc. and contributorsCOMMENT
LOWc++/src/kj/filesystem.h41 // A Path identifies a file in a directory tree.COMMENT
LOWc++/src/kj/filesystem.h61 // better result.COMMENT
LOWc++/src/kj/filesystem.h121 Path eval(StringPtr pathText) &&;COMMENT
LOWc++/src/kj/filesystem.h181 // the colon, will become the first component of the path, e.g. "c:\foo" becomes {"c:", "foo"}.COMMENT
LOWc++/src/kj/filesystem.h201 // names like "con".COMMENT
LOWc++/src/kj/filesystem.h301// filesystem access in practice. The filesystem drivers on Linux are written to assume they canCOMMENT
LOWc++/src/kj/filesystem.h361 // If they report the same hashCode, then they may or may not be the same object.COMMENT
LOWc++/src/kj/filesystem.h421 // Depending on the capabilities of the OS and filesystem, the mapping may or may not reflectCOMMENT
LOWc++/src/kj/filesystem.h461 // back at all.COMMENT
LOWc++/src/kj/filesystem.h501 // visible in other mappings of the file on the same system and will eventually be written backCOMMENT
LOWc++/src/kj/filesystem.h561 virtual Maybe<Own<const ReadableDirectory>> tryOpenSubdir(PathPtr path) const = 0;COMMENT
LOWc++/src/kj/filesystem.h581 // Mode for opening a file (or directory) for write.COMMENT
LOWc++/src/kj/filesystem.h601COMMENT
LOWc++/src/kj/filesystem.h621COMMENT
LOWc++/src/kj/filesystem.h681 // holes in the target file where holes exist in the source file.COMMENT
LOWc++/src/kj/filesystem.h701 // handle-relative paths, KJ may stop locking directories in this way, so do not rely on thisCOMMENT
LOWc++/src/kj/filesystem.h721 //COMMENT
LOWc++/src/kj/filesystem.h741 // `tryCommit()` may return false based on the CREATE/MODIFY bits passed as the WriteMode whenCOMMENT
LOWc++/src/kj/filesystem.h761 // filesystem.COMMENT
LOWc++/src/kj/filesystem.h821 // Construct a directory which, when ready, will be atomically moved to `path`, replacingCOMMENT
LOWc++/src/kj/filesystem.h861 // implementations of tryTransfer() in cases where the target directory would otherwise fail orCOMMENT
LOWc++/src/kj/filesystem.h881 // APIs. If you're interested, see the TODO(security) in filesystem-disk-win32.c++.COMMENT
LOWc++/src/kj/filesystem.h901class Filesystem {COMMENT
LOWc++/src/kj/filesystem.h941Own<File> newMemfdFile(uint flags = 0);COMMENT
LOWc++/src/kj/filesystem.h961// which would expand it will throw.COMMENT
LOWc++/src/kj/async-unix.h1// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributorsCOMMENT
LOWc++/src/kj/async-unix.h21COMMENT
LOWc++/src/kj/async-unix.h41// (Note that OpenBSD's kqueue(2) doesn't support user event filters yet)COMMENT
LOWc++/src/kj/async-unix.h61struct kevent;COMMENT
LOWc++/src/kj/async-unix.h81 // particular, note that after a fork(), a UnixEventPort created in the parent process willCOMMENT
517 more matches not shown…
Decorative Section Separators10 hits · 30 pts
SeverityFileLineSnippetContext
MEDIUMrelease.sh166 # ======================================================================================COMMENT
MEDIUMrelease.sh202 # ======================================================================================COMMENT
MEDIUMrelease.sh244 # ======================================================================================COMMENT
MEDIUMrelease.sh280 # ======================================================================================COMMENT
MEDIUMrelease.sh313 # ======================================================================================COMMENT
MEDIUMrelease.sh341 # ======================================================================================COMMENT
MEDIUMrelease.sh347 # ======================================================================================COMMENT
MEDIUMc++/src/capnp/compiler/capnp-test.sh52# ========================================================================================COMMENT
MEDIUMc++/src/capnp/compiler/capnp-test.sh87# ========================================================================================COMMENT
MEDIUMc++/src/capnp/compiler/capnp-test.sh105# ========================================================================================COMMENT
AI Slop Vocabulary5 hits · 15 pts
SeverityFileLineSnippetContext
MEDIUMc++/src/kj/common.h808// that type. This is useful to use as e.g. a parameter to a function because it will be robustCOMMENT
MEDIUMc++/src/kj/common.h813// of that type. This is useful to use as e.g. a parameter to a function because it will be robustCOMMENT
MEDIUMc++/src/kj/async-inl.h157 // potentially other objects that commonly live on the end of a promise chain can also leverageCOMMENT
MEDIUMc++/src/kj/async-inl.h1644 // to a dangling pointer. Essentially, WeakFulfiller is reference counted, although theCOMMENT
MEDIUMc++/src/capnp/serialize-text.h38 // This format is useful for debugging or human input, but it is not a robust alternativeCOMMENT
Fake / Example Data6 hits · 8 pts
SeverityFileLineSnippetContext
LOW⚡doc/cxx.md69 alicePhones[0].setNumber("555-1212");CODE
LOW⚡doc/cxx.md78 bobPhones[0].setNumber("555-4567");CODE
LOW⚡doc/cxx.md80 bobPhones[1].setNumber("555-7654");CODE
LOWdoc/cxx.md523 phone0.set("number", "555-1212");CODE
LOWdoc/cxx.md537 bobPhones[0].setNumber("555-4567");CODE
LOWdoc/cxx.md539 bobPhones[1].setNumber("555-7654");CODE
Example Usage Blocks2 hits · 3 pts
SeverityFileLineSnippetContext
LOWc++/src/kj/main.h205 // Example usage:COMMENT
LOWc++/src/kj/async.h431// Example usage:COMMENT
Modern AI Meta-Vocabulary1 hit · 2 pts
SeverityFileLineSnippetContext
MEDIUMdoc/cxxrpc.md27Cap'n Proto's RPC is based on the [KJ library](cxx.html#kj-library)'s event-driven concurrencyCODE
TODO Padding1 hit · 2 pts
SeverityFileLineSnippetContext
LOWc++/src/kj/array.h352 // TODO: implement for complex T types without creating `size` instances first.COMMENT
Slop Phrases1 hit · 1 pts
SeverityFileLineSnippetContext
LOWrelease.sh113 echo "Don't forget to push changes:"CODE
Unused Imports1 hit · 1 pts
SeverityFileLineSnippetContext
LOWdoc/_plugins/capnp_lexer.py4CODE