File Naming Rules

Status: house convention for committed filenames. Every committed document or asset follows these conventions: lowercase, dash-separated, ASCII, ISO dates. This is the filename companion to commits.md (the same discipline applied to commit text): a name a future reader can predict, type, and glob without surprises.

Scope

This rule governs committed documents and assets: scanned documents, photos, exports, dated records, and the other non-code files a repository accumulates. Two classes are out of scope and are never flagged by the audit below, because a different authority already names them:

Source code. A source file follows its language's own naming convention. A Swift type file is PascalCase, named for the single type it holds, and a framework-style internal type may carry a leading underscore (_ConditionalContent.swift); a Go file is lowercase; and so on. That language convention is the authority for those files, and the code-style rule of each language domain owns it. This rule does not override it, so source trees are excluded from the audit.
Conventional and tool-mandated names. The uppercase names a tool or ecosystem expects verbatim: the repository-root files LICENSE, CHANGELOG, CONTRIBUTING, CODEOWNERS, NOTICE, AUTHORS, README, and VERSION; the platform infrastructure under .github/ (ISSUE_TEMPLATE/, PULL_REQUEST_TEMPLATE, FUNDING.yml); and the build and package manifests a toolchain loads by an exact name (Package.swift, Package.resolved, Package@swift-5.9.swift, Dockerfile, Makefile, Gemfile, Rakefile, Podfile, Cartfile, Fastfile). Renaming any of them would break the tool that looks for them.

General rules

Lowercase only: no uppercase letters in filenames.
Dashes for separators: use - instead of spaces, underscores, or camelCase.
No spaces: ever.
No special characters: no accented letters, (), [], &. Transliterate accented characters to plain ASCII (for example, c-with-caron to c, s-with-caron to s, d-with-stroke to dj).
No trailing dots: remove any dot before the file extension.
ASCII only: filenames must be plain ASCII.

Date format in filenames

Always use the ISO format YYYY-MM-DD:

30.11.2023 -> 2023-11-30
11.03.2024. -> 2024-03-11
Mar 24, 2025 -> 2025-03-24

Document naming patterns

Scanned documents

Scan MMM DD, YYYY at HH.MM.pdf    -> scan-YYYY-MM-DD-HH-MM.pdf
Scan DD.MM.YYYY. at HH.MM.pdf     -> scan-YYYY-MM-DD-HH-MM.pdf
Scan DD MMM YYYY at HH.MM.pdf     -> scan-YYYY-MM-DD-HH-MM.pdf

Photos

IMG_XXXX.jpeg                      -> keep as-is (acceptable)
IMG_XXXX.HEIC                      -> convert to IMG_XXXX.jpg
Photo DD-MM-YYYY.heic              -> photo-YYYY-MM-DD.jpg (convert + rename)

Dated documents

<type>-<description>-YYYY-MM-DD.<ext>

Use a date suffix only when the document is date-specific; omit it otherwise. Neutral examples:

invoice-2024-03-01.pdf
design-notes-2025-06-14.md
release-checklist.md          # not date-specific, no suffix

Renaming existing files

When renaming, use git mv to preserve history:

git mv "Old File Name.pdf" "old-file-name.pdf"

Commit: chore(files): normalize filenames

Audit (before any processing)

Run these in the repo before reporting counts:

Point <repo> at the document and asset directories the rule governs, or add a -not -path "*/<source-dir>/*" for each source tree (Sources, Tests, src), so the queries do not flag source files that follow their language convention (see Scope).

# Files with spaces
find <repo> -name "* *" -not -path "*/.git/*"

# Files with uppercase (documents and assets only; source files and the
# conventional or tool-mandated names of the Scope section are out of scope)
find <repo> -regex ".*/[^/]*[A-Z][^/]*" -not -path "*/.git/*" -not -path "*/.github/*" \
  -not -name "README*" -not -name "LICENSE*" -not -name "CHANGELOG*" \
  -not -name "CONTRIBUTING*" -not -name "CODEOWNERS" -not -name "NOTICE" \
  -not -name "AUTHORS" -not -name "VERSION" \
  -not -name "Package.swift" -not -name "Package.resolved" -not -name "Package@*.swift" \
  -not -name "Dockerfile" -not -name "Makefile" -not -name "Gemfile" \
  -not -name "Rakefile" -not -name "Podfile" -not -name "Cartfile" -not -name "Fastfile"

# Files with underscores (excluding .git and the tool-mandated .github tree)
find <repo> -name "*_*" -not -path "*/.git/*" -not -path "*/.github/*"

# HEIC files
find <repo> \( -name "*.heic" -o -name "*.HEIC" \) -not -path "*/.git/*"

Run over the documents and assets in scope, a clean repo returns nothing from the first three queries: the README and conventional-root-file exclusions cover the in-scope exceptions, and the source-tree exclusion keeps the audit off code, which the language's own code-style rule governs (Scope).

Skip list

Some asset paths legitimately carry vendor-supplied names and are exempt from the audit. Document the skip paths per repo (for example, browser-extension resource folders, generated asset bundles, vendor media dumps). Keep the list short and justified: every exemption is a name a reader cannot predict, so it must earn its place.

Companion rules

commits.md: the same lowercase/dashed/ASCII/ISO discipline applied to commit messages and branch names.
no-shortcuts-first-principles.md: an unpredictable filename committed "just this once" is a small shortcut that compounds across a tree.

Why this exists

Filenames are an interface. A predictable scheme means a reader can guess a path, a glob can match a set, and a sort orders by date without a parser. Mixed case, spaces, and locale-specific characters break globs, confuse case-insensitive filesystems, and force quoting. The convention costs nothing at creation time and saves every later reader.

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