Function validate_blocks 

fn validate_blocks(
    file: &str,
    user: &UserSection,
    tool_ids: &HashSet<String>,
    strict_refs: bool,
) -> Result<ExtractedBlocks, PackError>

Validates and extracts metadata from the fenced blocks in a user section.

This function walks the user’s fenced blocks, validates block sequences and references, and collects extracted metadata into an ExtractedBlocks struct:

• Tool blocks must contain a single ${...} reference that matches a known tool ID; if followed by a JSON or XML block it is treated as a payload pair (payload must be a ${...} ref when strict_refs is true).
• Standalone JSON or XML blocks are invalid and produce an error.
• Constraints blocks produce one extracted constraint per non-empty, non-comment line.
• Tools blocks list tool IDs (one per line, optionally prefixed with -) which are validated against tool_ids and collected into tool_refs.
• Rag blocks store their trimmed content as the optional rag_config.
• New config kinds (Adapter, Memory, Policy, Injection, Provider, Cache, Trajectory, Agent, Manifest) are accepted and skipped for later processing.

Errors are returned as PackError::Markdown with file/line context for structural or validation failures.

Returns

The collected ExtractedBlocks containing constraints, tool_refs, and optional rag_config.

Examples

use std::collections::HashSet;

// Construct a simple user section with a constraints block
let user = UserSection {
    content: String::new(),
    blocks: vec![FencedBlock {
        kind: FenceKind::Constraints,
        header_name: None,
        content: "must do X\n# comment\nmust not do Y\n".into(),
        line: 1,
    }],
};

let tool_ids: HashSet<String> = HashSet::new();
let extracted = validate_blocks("file.md", &user, &tool_ids, false).unwrap();
assert_eq!(extracted.constraints, vec!["must do X".to_string(), "must not do Y".to_string()]);