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openspec/archive/2026-04-19-enterprise-exif/specs/exif/spec.md

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+# Capability Spec: exif
+
+**Package**: `@suaveplan/exif`
+**Version**: 0.0.0 (genesis)
+**Status**: ADDED
+
+---
+
+## ADDED Requirements
+
+### EXIF-01 — Format detection
+`detectImageFormat(bytes)` MUST identify JPEG, PNG, WebP, TIFF, HEIC (ISOBMFF), and the RAW families (CR2, CR3, NEF, ARW, RAF, ORF, RW2, DNG) by magic-byte sniffing. Unknown inputs MUST return `'unknown'`, not throw.
+
+### EXIF-02 — Read / write / strip dispatch
+`readMetadata(bytes, options?)` MUST dispatch to the format-specific reader and return a unified `ImageMetadata`. `writeMetadata(bytes, patch)` MUST apply a `MetadataPatch` and return a new buffer. `stripMetadata(bytes, options?)` MUST produce a buffer containing image data only; running it twice MUST be idempotent.
+
+### EXIF-03 — IFD codec
+`parseTiff(bytes, options?)` MUST return `ParsedTiff` with every IFD, entry, and sub-IFD. `buildTiff(input)` MUST produce a byte buffer that round-trips through `parseTiff` to an equal `ParsedTiff`. Entry type widths MUST follow `TIFF_TYPE_SIZE`.
+
+### EXIF-04 — GPS
+`decimalToDms` and `dmsToDecimal` MUST round-trip within 1e-7 degrees. `gpsToIsoTimestamp` and `isoToGpsFields` MUST round-trip to second precision.
+
+### EXIF-05 — ICC
+`readIccProfile` MUST return `IccProfile` with header, tag table, and parsed tag values. `validateIccProfile` MUST reject profiles with invalid size, version, or checksum. `classifyProfile` MUST detect `sRGB`, `AdobeRGB`, `DisplayP3` reliably for canonical profiles.
+
+### EXIF-06 — IPTC / XMP
+`readIptc` / `writeIptc` MUST support IIM records 1, 2 with UTF-8 and ISO-8859-1 charsets. `readXmp` MUST return an `XmpData` tree (scalars, structs, language-alternatives). `XMP_NAMESPACES` MUST expose the canonical URI per prefix.
+
+### EXIF-07 — MakerNotes
+`decodeMakerNote` MUST dispatch to the correct vendor decoder. Nikon and Sony encrypted MakerNote tags MUST be decoded via `nikonDecrypt` / `sonyDecrypt` using the serial+shutter-derived keys. `decodeAppleMakerNote` MUST decode embedded bplist via `decodeBplist`.
+
+### EXIF-08 — Safety
+All readers MUST operate on bounded `ByteReader` views and MUST throw `EXIF.BUFFER_OVERRUN` rather than reading past the buffer end. No reader MUST allocate buffers larger than the input.
+
+### EXIF-09 — Observability
+Every read/write/strip MUST record the corresponding OTel histogram with label `format`.