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lanework/Kanban/Storage/FrontmatterFields.swift
T
rzen d5ad21c3da The board wears a picture — background becomes a mapping, and the window chrome follows it under a thin frost
background is {color:, image:} and only a mapping at every level; the board's image paints the full window under a transparent title bar, with a thin-material frost strip keeping the chrome legible and the standard accommodations intact.

Claude-Session: https://claude.ai/code/session_014PtZdPwqZuqEDLc6wZMtEy
2026-08-07 10:15:03 -04:00

315 lines
18 KiB
Swift

import Foundation
import Yams
/// One top-level frontmatter entry: what YAML made of it plus the text as written.
public struct FrontmatterField: Sendable, Equatable {
public let key: String
public let value: YAMLValue
public let rawValue: String
}
/// The result of reading a typed field — **the document's reading, before any policy**. Lenient
/// fields (colors, icons, `width`) coerce where a sensible reading exists (01-storage-format.md
/// § Frontmatter) and only fall back to `.malformed` — rendered as the field's default — when none
/// does. Structural fields (`schema`, `order`) have no coercion at all at this layer: a value that
/// is not an integer, or not a finite number, is `.malformed` and nothing here decides what that
/// costs. **What it costs is the rulebook's** (`IntegrityRules`): a malformed `schema` refuses the
/// load, while a malformed or missing `order` below the board root reads as append-at-end
/// (re-ruled 2026-07-31) — one shape, two policies, and this type carries neither.
public enum FieldValue<Value: Sendable & Equatable>: Sendable, Equatable {
case missing
case valid(Value)
case malformed(raw: String)
public var value: Value? {
if case let .valid(value) = self { return value }
return nil
}
public var isMissing: Bool {
if case .missing = self { return true }
return false
}
public var isMalformed: Bool {
if case .malformed = self { return true }
return false
}
/// The value as written, for a malformed field.
public var rawText: String? {
if case let .malformed(raw) = self { return raw }
return nil
}
}
/// One **lenient** field that had no sensible reading and fell back to its default — the coerce
/// tier's observability record (01-storage-format.md § Frontmatter, ruled 2026-07-29: "A
/// no-sensible-reading fallback logs: field, path, and raw text, carried as coerce-tier entries in the
/// integrity service's Defect stream").
///
/// **Two of the three facts, because this layer only has two.** `FrontmatterFields` is a pure reading
/// of one document's bytes and has no idea which file it came from, so the *path* is attached by the
/// loader, which does (`CoercedFrontmatter`). Threading a path down here to satisfy the record's shape
/// would put filesystem context into the one layer that is deliberately free of it.
public struct CoercedField: Sendable, Equatable {
/// The frontmatter key, as the schema spells it.
public let key: String
/// The value exactly as written — the raw source span, which is the only form worth recording:
/// this exists so that a shape observed in the wild can later be promoted to a heuristic heal, and
/// a normalized rendering of a value nobody could read would defeat that.
public let raw: String
public init(key: String, raw: String) {
self.key = key
self.raw = raw
}
}
extension FrontmatterDocument {
// MARK: - The coerce tier's own report
/// Every **lenient** field in this document that had no sensible reading, in schema order — the
/// coerce tier's whole observability contribution (01-storage-format.md § Frontmatter, ruled
/// 2026-07-29: "the family posture: every silent recovery leaves a trace").
///
/// **Read-side only, and nothing branches on it.** The values still render as their defaults —
/// untitled placeholder, width 1, no color, no icon, no timestamp — the bytes on disk are still
/// preserved verbatim, and no banner is raised. The list exists so the fallback is *visible*: it is
/// "the one place where an observed-in-the-wild shape can later be promoted to a heuristic heal or
/// a notice".
///
/// **The structural fields are absent, and so is `deleted`.** `schema` and `order` are read
/// through the rulebook rather than here (`IntegrityRules.resolvedSchema`/`resolvedOrder`),
/// because their readings depend on something this layer cannot see — *which level the file sits
/// at*: the root's `schema` refuses, a lane's or card's defaults to 1, and `order` below the root
/// reads as append-at-end (re-ruled 2026-07-31). Those two make their own `CoercedField`s, which
/// the loader concatenates with this list; they also cover the shape a pure document reading
/// cannot produce at all — an **absent** key, which has no `rawText` to record. `deleted` is the
/// odd one out on purpose: its rule is *presence, not validity* (a malformed `deleted` still
/// deletes — `Lane`/`Card.isDeleted`), so nothing falls back to a default and the migration
/// reports it under its own defect anyway.
///
/// A document whose fields all read cleanly answers `[]`, which is the overwhelmingly common case
/// and costs one pass over the lenient fields.
public var coercedFields: [CoercedField] {
var found: [CoercedField] = []
func record(_ key: String, _ field: FieldValue<some Sendable & Equatable>) {
guard let raw = field.rawText else { return }
found.append(CoercedField(key: key, raw: raw))
}
record(FrontmatterKeys.title, title)
record(FrontmatterKeys.width, width)
record(FrontmatterKeys.created, created)
record(FrontmatterKeys.modified, modified)
record(FrontmatterKeys.modifiedBy, modifiedBy)
record(FrontmatterKeys.author, author)
record(FrontmatterKeys.background, background)
// **`background` can contribute two entries**, because the one key holds two readings once
// it is written as a mapping (`FrontmatterDocument.backgroundImage`). Both are filed under
// the key the schema spells, which is the key an author would go and fix; they are told
// apart by their raw text, since each quotes the subvalue that could not be read. A mapping
// whose colour reads fine and whose image does not still leaves a trace, which is the whole
// contract here.
record(FrontmatterKeys.background, backgroundImage)
record(FrontmatterKeys.icon, icon)
record(FrontmatterKeys.iconColor, iconColor)
record(FrontmatterKeys.kind, kind)
return found
}
// MARK: - Structural (no coercion here — `IntegrityRules` decides what `.malformed` costs)
public var schema: FieldValue<Int> {
read(FrontmatterKeys.schema) { value, _ in if case let .int(value) = value { value } else { nil } }
}
/// A non-finite reading (`.nan`, `.inf`) has no place in the total order the tie-break and
/// midpoint math assume (01-storage-format.md § Frontmatter, settled) — it is `.malformed` here,
/// never a `.valid(Double.nan)` silently poisoning every comparison downstream. An `Int` reading
/// is always finite, so only the `.double` case needs the check.
///
/// Below the board root `.malformed` and `.missing` are one reading — append-at-end, coerce-tier
/// (re-ruled 2026-07-31, `IntegrityRules.resolvedOrder`) — but they stay two shapes here, because
/// the coerce record wants the text as written and only one of them has any.
public var order: FieldValue<Double> {
read(FrontmatterKeys.order) { value, _ in
switch value {
case let .int(value): Double(value)
case let .double(value): value.isFinite ? value : nil
default: nil
}
}
}
// MARK: - Lenient (coerce where a sensible reading exists, else malformed → UI default)
/// Any scalar coerces to the text the author typed — a quoted string's own text (quotes and
/// escapes already resolved by the parser), or an unquoted scalar's exact source span
/// (`title: 2048` reads as `"2048"`). Only a sequence or mapping — no scalar reading exists
/// — is malformed.
public var title: FieldValue<String> { read(FrontmatterKeys.title, Self.string) }
public var icon: FieldValue<String> { read(FrontmatterKeys.icon, Self.string) }
public var iconColor: FieldValue<String> { read(FrontmatterKeys.iconColor, Self.string) }
/// The `background` mapping's **colour** — a palette name or a `#RRGGBB[AA]` hex, read through
/// the same scalar coercion every other string field uses.
///
/// **`background` is a mapping, and only a mapping** (01-storage-format.md § Frontmatter, ruled
/// 2026-08-06): `{color: "#112233", image: sunset.jpg}`, either subkey absent, unknown subkeys
/// tolerated. A bare scalar — `background: green` — has **no reading at all** and is
/// `.malformed`: it renders as no colour, files a coerce-tier trace, and stays on disk exactly as
/// written, which is the same lenient degrade a colour nobody can resolve already gets.
///
/// That is a ruling about the *schema*, not a migration: nothing had shipped when it was made, so
/// there is no legacy spelling to keep alive, no version bump, and no healing machinery. One key,
/// one shape, and a field whose type does not depend on which subkeys the author happened to
/// want.
///
/// **One reader for all three levels, deliberately.** A lane's and a card's `background` mean
/// colour and nothing else — they are edge accents, and only the board consumes an image
/// (03-board-ui.md § Styling ▸ Capabilities) — but the *shape* is uniform, so a lane writes
/// `{color: fern}` exactly as the board does and nothing below has to know which level it is
/// reading.
///
/// A mapping carrying no `color` — an image-only background, or an explicit `color: null` —
/// reads `.missing`, which is exactly "no colour" and renders the level's default; that is an
/// absence, not a failure, and it files no trace. A `color` that is itself a sequence or mapping
/// has no scalar reading and is `.malformed` like any other.
public var background: FieldValue<String> {
backgroundReading(FrontmatterKeys.Background.color, reportsShape: true)
}
/// The `background` mapping's **image** — a path relative to the board root, board-only in
/// meaning (`BoardModel` carries it; `Lane` and `Card` deliberately do not).
///
/// `.missing` for every shape that is not a mapping, including the retired scalar: a value the
/// schema cannot read is **one** unreadable value, and the colour reading above already reports
/// it. Two `.malformed`s off one key would file the same defect twice and say the file named an
/// image when it did nothing of the kind.
///
/// **Where the path leads is not this layer's question.** Whether it resolves inside the board
/// root, and whether the bytes are an image at all, belongs to the renderer
/// (`BoardBackdrop.imageURL(named:inBoardRoot:)`); this is the document's reading of what was
/// written, and an unresolvable path degrades exactly like an unrecognized colour — paint
/// nothing, change nothing on disk.
public var backgroundImage: FieldValue<String> {
backgroundReading(FrontmatterKeys.Background.image, reportsShape: false)
}
/// Width multiplier. An exact-integer reading — from an int, a double, or a numeric string —
/// always coerces: at or above 1 to itself (`"2"`, `2.0` → `2`), below 1 to 1 (**ranges are
/// part of the sensible reading**, 01-storage-format.md § Frontmatter, settled — the table's
/// "≥ 1" is a validity bound on the coerced reading, not a gate on which readings are
/// sensible). Everything else — fractional, non-numeric, bool, a sequence/mapping — has no
/// integer reading at all and is malformed, rendering as the default 1.
public var width: FieldValue<Int> {
read(FrontmatterKeys.width) { value, _ in
switch value {
case let .int(value): value >= 1 ? value : 1
case let .double(value): Self.exactIntWidth(value)
case let .string(text): Double(text).flatMap(Self.exactIntWidth)
default: nil
}
}
}
public var created: FieldValue<Date> { read(FrontmatterKeys.created) { value, _ in Self.date(value) } }
public var modified: FieldValue<Date> { read(FrontmatterKeys.modified) { value, _ in Self.date(value) } }
public var deleted: FieldValue<Date> { read(FrontmatterKeys.deleted) { value, _ in Self.date(value) } }
/// Schema-owned, not an unknown key: the app clears it on every app-mediated write.
public var modifiedBy: FieldValue<String> { read(FrontmatterKeys.modifiedBy, Self.string) }
/// A comment's self-reported `author` — lenient like every other string field, and **content**
/// rather than overlay: no app write ever clears it (01-storage-format.md § Enhanced schema; see
/// `FrontmatterKeys.author`). On any other kind the key is an ordinary unknown one; reading it
/// here costs the same one pass and keeps the coerce tier's trace complete for the one kind whose
/// field table names it.
public var author: FieldValue<String> { read(FrontmatterKeys.author, Self.string) }
/// The object's kind as written — `board`, `lane`, `card` (01-storage-format.md § Frontmatter,
/// re-ruled 2026-07-29). Lenient like every other string field: any scalar coerces to the text
/// the author typed, and **the value is never policed** — a reading outside the schema's three
/// is a perfectly good `.valid` here, and the one consumer that acts on it (the trash's
/// discriminator, `IntegrityRules.trashKind`) falls through to shape for anything it does not
/// recognize rather than correcting the file.
///
/// `.missing` — no key, or an explicit null — is what the on-touch backfill answers to.
public var kind: FieldValue<String> { read(FrontmatterKeys.kind, Self.string) }
// MARK: -
/// One subkey's reading out of the `background` mapping. It is `read(_:_:)`'s shape with one
/// extra step, and it cannot *be* `read(_:_:)`: that helper's transform answers `nil` for "no
/// sensible reading", where a mapping with no such subkey has to answer `.missing` — an absent
/// subkey is an absent value, not an unreadable one, and reporting it as a coerce-tier fallback
/// would file a defect against every image-only background in existence.
///
/// `reportsShape` is the whole difference between the two readers above, and it is about the
/// **key's** shape rather than the subkey's: a value that is not a mapping at all — the retired
/// scalar, a sequence — is one unreadable value, so exactly one reader reports it. The colour is
/// that reader because the colour is what the key means when it has no subkeys to speak of; the
/// image stays `.missing`, since a file that never wrote a mapping never claimed to name a
/// picture.
///
/// **A subvalue's malformed raw is the parse's rendering, not a source span.** `rawValue(for:)`
/// addresses top-level keys, so a subkey has no span to quote; the coerce record takes what the
/// parse retained (`YAMLValue.description`), which is the most this shape can honestly offer and
/// still names what could not be read. The key's *own* malformed raw is the span, as always.
private func backgroundReading(_ subkey: String, reportsShape: Bool) -> FieldValue<String> {
guard let value = value(for: FrontmatterKeys.background) else { return .missing }
if case .null = value { return .missing }
guard case let .mapping(pairs) = value else {
guard reportsShape else { return .missing }
return .malformed(raw: rawValue(for: FrontmatterKeys.background) ?? value.description)
}
guard let subvalue = pairs.first(where: { $0.key == .string(subkey) })?.value else { return .missing }
if case .null = subvalue { return .missing }
let raw = subvalue.description
return Self.string(subvalue, raw: raw).map(FieldValue.valid) ?? .malformed(raw: raw)
}
private func read<Value>(_ key: String, _ transform: (YAMLValue, String) -> Value?) -> FieldValue<Value> {
guard let value = value(for: key) else { return .missing }
if case .null = value { return .missing }
let raw = rawValue(for: key) ?? value.description
if let typed = transform(value, raw) { return .valid(typed) }
return .malformed(raw: raw)
}
/// A quoted string reads as its own (already-unquoted, already-unescaped) text; any other
/// scalar reads as its raw source span — what the author typed. Only a sequence/mapping has
/// no sensible string reading.
private static func string(_ value: YAMLValue, raw: String) -> String? {
switch value {
case let .string(text): text
case .int, .double, .bool, .date: raw
default: nil
}
}
/// An integer-valued double or numeric string coerces — below 1 to 1, at or above 1 to the
/// value itself; a fractional reading, a non-numeric one, or one outside `Int` range on the
/// high end has no sensible width reading at all. The high-end guard is what makes `Int(value)`
/// safe below; there is no matching low-end guard because anything below 1 short-circuits to
/// the literal `1` without ever converting the (possibly enormous negative) double to `Int`.
private static func exactIntWidth(_ value: Double) -> Int? {
guard value.truncatingRemainder(dividingBy: 1) == 0, value <= Double(Int.max) else { return nil }
return value >= 1 ? Int(value) : 1
}
/// A quoted timestamp reads the same as an unquoted one — same YAML 1.1 timestamp grammar,
/// a superset of ISO-8601. Anything that isn't a valid timestamp either way has no sensible
/// date reading and is malformed; per the tombstone rule (`Lane`/`Card.isDeleted`), a
/// malformed `deleted` still deletes — presence, not validity, is what counts.
private static func date(_ value: YAMLValue) -> Date? {
switch value {
case let .date(date): date
case let .string(text): Date.construct(from: Node.Scalar(text))
default: nil
}
}
}