commit pi sessions

pi/.pi/agent/prompts/test/support/frontmatter.ts

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+/**
+ * Minimal YAML frontmatter parser tailored to the prompt workflow files
+ * in this directory. Mirrors the subset of YAML that the existing `c-*.md`
+ * and `p-*.md` files actually use:
+ *
+ *   key: value              -> string
+ *   key: "quoted value"     -> string (quotes stripped)
+ *   key:                    -> block scalar (everything more-indented is
+ *                              collected, de-indented, and returned as one
+ *                              string with newlines)
+ *
+ * Comments (`# ...`) and blank lines are skipped. Quoted strings have
+ * their quotes stripped, matching the convention used in the rest of the
+ * repo (no nested quoting or escapes are needed by the fixtures).
+ */
+export interface ParsedDoc {
+	frontmatter: Record<string, string>;
+	body: string;
+}
+
+function stripComment(line: string): string {
+	const idx = line.indexOf("#");
+	// Only treat `#` as a comment when it appears at start-of-line or
+	// after whitespace; otherwise the `#` is part of a value (it never
+	// is in this repo, but it keeps the parser robust).
+	if (idx === -1) return line;
+	const before = line.slice(0, idx);
+	if (/^\s*$/.test(before)) return before;
+	return line;
+}
+
+function deIndentBlock(block: string): string {
+	const lines = block.split("\n");
+	const indents = lines
+		.filter((l) => l.trim() !== "")
+		.map((l) => l.match(/^[ \t]*/)?.[0].length ?? 0);
+	const min = indents.length === 0 ? 0 : Math.min(...indents);
+	if (min === 0) return block.replace(/^\n+/, "");
+	return lines
+		.map((l) => (l.length >= min ? l.slice(min) : l))
+		.join("\n")
+		.replace(/^\n+/, "");
+}
+
+export function parseFrontmatter(content: string): ParsedDoc {
+	const normalized = content.replace(/\r\n/g, "\n");
+	if (!normalized.startsWith("---")) {
+		return { frontmatter: {}, body: normalized };
+	}
+
+	// The closing fence is `\n---` (optionally followed by whitespace/eol).
+	const endIndex = normalized.indexOf("\n---", 3);
+	if (endIndex === -1) {
+		return { frontmatter: {}, body: normalized };
+	}
+
+	const block = normalized.slice(3, endIndex);
+	const body = normalized.slice(endIndex + 4).replace(/^\s+/, "");
+
+	const frontmatter: Record<string, string> = {};
+	let currentKey: string | null = null;
+	let currentBlock: string[] | null = null;
+	let currentIndent = -1;
+
+	const flush = () => {
+		if (currentKey === null || currentBlock === null) return;
+		frontmatter[currentKey] = deIndentBlock(currentBlock.join("\n"));
+		currentKey = null;
+		currentBlock = null;
+		currentIndent = -1;
+	};
+
+	for (const rawLine of block.split("\n")) {
+		const line = stripComment(rawLine);
+		if (line.trim() === "") {
+			// Preserve blank lines inside an open block scalar, otherwise
+			// ignore them between keys.
+			if (currentBlock !== null) currentBlock.push("");
+			continue;
+		}
+
+		const indent = line.match(/^[ \t]*/)?.[0].length ?? 0;
+		if (currentKey !== null && currentBlock !== null && indent > currentIndent) {
+			currentBlock.push(line);
+			continue;
+		}
+
+		flush();
+
+		const match = line.match(/^([A-Za-z][\w-]*):\s*(.*)$/);
+		if (!match) continue;
+		const key = match[1];
+		const raw = match[2].trim();
+
+		if (raw === "" || raw === ">" || raw === "|-" || raw === ">-" || raw === "|") {
+			currentKey = key;
+			currentBlock = [];
+			currentIndent = indent;
+		} else {
+			const quoted =
+				(raw.startsWith('"') && raw.endsWith('"')) ||
+				(raw.startsWith("'") && raw.endsWith("'"));
+			frontmatter[key] = quoted ? raw.slice(1, -1) : raw;
+		}
+	}
+
+	flush();
+
+	return { frontmatter, body };
+}
+
+/**
+ * Split a `chain:` frontmatter value into individual step names.
+ * Mirrors the upstream convention of ` -> ` as the delimiter and trims
+ * whitespace from each step.
+ */
+export function parseChain(value: string | undefined): string[] {
+	if (!value) return [];
+	return value
+		.split(" -> ")
+		.map((s) => s.trim())
+		.filter((s) => s.length > 0);
+}