diff --git a/tools/fn_complexity.py b/tools/fn_complexity.py
new file mode 100755
index 0000000..84212cb
--- /dev/null
+++ b/tools/fn_complexity.py
@@ -0,0 +1,181 @@
+#!/usr/bin/env python3
+"""Analyze per-function complexity metrics for Rust source files.
+
+Reports: function name, line count, max nesting depth, and file location.
+Sorted by line count (descending) to surface the largest functions first.
+
+Usage:
+    python3 tools/fn_complexity.py src/worker.rs
+    python3 tools/fn_complexity.py src/           # recurse into directory
+    python3 tools/fn_complexity.py src/ --json     # JSON output
+    python3 tools/fn_complexity.py src/ --min-lines 20  # filter small fns
+"""
+
+import argparse
+import json
+import os
+import re
+import sys
+from dataclasses import dataclass, asdict
+from pathlib import Path
+
+
+@dataclass
+class FnMetric:
+    file: str
+    name: str
+    start_line: int
+    end_line: int
+    lines: int
+    max_depth: int
+    has_unsafe: bool
+
+    @property
+    def location(self) -> str:
+        return f"{self.file}:{self.start_line}"
+
+
+# Matches fn declarations (free functions, methods, trait impls)
+FN_PATTERN = re.compile(
+    r'^\s*(?:pub(?:\(crate\))?\s+)?(?:async\s+)?fn\s+(\w+)'
+)
+
+# Matches impl blocks to qualify method names
+IMPL_PATTERN = re.compile(
+    r'^\s*impl(?:<[^>]*>)?\s+(?:(\w+(?:<[^>]*>)?)\s+for\s+)?(\w+)'
+)
+
+
+def analyze_file(path: str) -> list[FnMetric]:
+    """Parse a single Rust file and extract function metrics."""
+    with open(path) as f:
+        lines = f.readlines()
+
+    metrics = []
+    current_impl = None
+    brace_depth = 0
+    fn_stack: list[tuple[str, int, int, bool]] = []  # (name, start_line, start_depth, has_unsafe)
+
+    for i, line in enumerate(lines, 1):
+        stripped = line.rstrip()
+
+        # Track impl blocks for method qualification
+        impl_match = IMPL_PATTERN.match(stripped)
+        if impl_match and '{' in stripped:
+            trait_name = impl_match.group(1)
+            type_name = impl_match.group(2)
+            if trait_name:
+                current_impl = f"{trait_name} for {type_name}"
+            else:
+                current_impl = type_name
+
+        # Detect function start
+        fn_match = FN_PATTERN.match(stripped)
+        if fn_match and '{' in stripped:
+            fn_name = fn_match.group(1)
+            if current_impl:
+                fn_name = f"{current_impl}::{fn_name}"
+            has_unsafe = 'unsafe' in stripped
+            fn_stack.append((fn_name, i, brace_depth, has_unsafe))
+
+        # Track brace depth
+        # Simple brace counting (ignores braces in strings/comments, good enough)
+        opens = stripped.count('{')
+        closes = stripped.count('}')
+        brace_depth += opens - closes
+
+        # Check for unsafe blocks within functions
+        if fn_stack and 'unsafe' in stripped and fn_match is None:
+            name, start, depth, _ = fn_stack[-1]
+            fn_stack[-1] = (name, start, depth, True)
+
+        # When a function's brace depth returns to entry level, it's done
+        while fn_stack and brace_depth <= fn_stack[-1][2]:
+            fn_name, start_line, _, has_unsafe = fn_stack.pop()
+            end_line = i
+            fn_lines = end_line - start_line + 1
+
+            # Calculate max nesting depth within this function
+            max_depth = 0
+            local_depth = 0
+            for j in range(start_line - 1, end_line):
+                if j < len(lines):
+                    local_depth += lines[j].count('{') - lines[j].count('}')
+                    max_depth = max(max_depth, local_depth)
+
+            # Reset impl context if we've left the impl block
+            if brace_depth == 0:
+                current_impl = None
+
+            metrics.append(FnMetric(
+                file=path,
+                name=fn_name,
+                start_line=start_line,
+                end_line=end_line,
+                lines=fn_lines,
+                max_depth=max_depth,
+                has_unsafe=has_unsafe,
+            ))
+
+    return metrics
+
+
+def collect_files(path: str) -> list[str]:
+    """Collect .rs files from a path (file or directory)."""
+    p = Path(path)
+    if p.is_file():
+        return [str(p)]
+    elif p.is_dir():
+        return sorted(str(f) for f in p.rglob('*.rs'))
+    else:
+        print(f"Error: {path} is not a file or directory", file=sys.stderr)
+        sys.exit(1)
+
+
+def main():
+    parser = argparse.ArgumentParser(description='Rust function complexity analyzer')
+    parser.add_argument('paths', nargs='+', help='Rust source files or directories')
+    parser.add_argument('--json', action='store_true', help='Output as JSON')
+    parser.add_argument('--min-lines', type=int, default=0,
+                       help='Only show functions with at least N lines')
+    parser.add_argument('--top', type=int, default=0,
+                       help='Show only the top N largest functions')
+    args = parser.parse_args()
+
+    all_metrics: list[FnMetric] = []
+    for path in args.paths:
+        for file in collect_files(path):
+            all_metrics.extend(analyze_file(file))
+
+    # Filter and sort
+    if args.min_lines:
+        all_metrics = [m for m in all_metrics if m.lines >= args.min_lines]
+    all_metrics.sort(key=lambda m: m.lines, reverse=True)
+    if args.top:
+        all_metrics = all_metrics[:args.top]
+
+    if args.json:
+        output = [asdict(m) for m in all_metrics]
+        print(json.dumps(output, indent=2))
+    else:
+        # Summary stats
+        if all_metrics:
+            total_fns = len(all_metrics)
+            avg_lines = sum(m.lines for m in all_metrics) / total_fns
+            max_fn = all_metrics[0]
+
+            print(f"Functions: {total_fns}, avg lines: {avg_lines:.1f}, "
+                  f"largest: {max_fn.name} ({max_fn.lines} lines)")
+            print()
+
+        # Table output
+        print(f"{'Lines':>5}  {'Depth':>5}  {'Location':<45}  {'Function'}")
+        print(f"{'─'*5}  {'─'*5}  {'─'*45}  {'─'*40}")
+        for m in all_metrics:
+            loc = f"{m.file}:{m.start_line}"
+            unsafe_marker = " [unsafe]" if m.has_unsafe else ""
+            print(f"{m.lines:>5}  {m.max_depth:>5}  {loc:<45}  {m.name}{unsafe_marker}")
+
+
+if __name__ == '__main__':
+    main()
diff --git a/tools/loc_analysis.py b/tools/loc_analysis.py
new file mode 100755
index 0000000..c7e6de2
--- /dev/null
+++ b/tools/loc_analysis.py
@@ -0,0 +1,164 @@
+#!/usr/bin/env python3
+"""Analyze line-of-code breakdown for Rust source files.
+
+Reports: logic, comments, blank, and string-literal lines per file.
+Helps track code reduction progress and identify embedded content.
+
+Usage:
+    python3 tools/loc_analysis.py src/
+    python3 tools/loc_analysis.py src/ crates/std/src/ --json
+    python3 tools/loc_analysis.py src/ --sort-by logic
+"""
+
+import argparse
+import json
+import re
+import sys
+from dataclasses import dataclass, asdict
+from pathlib import Path
+
+
+@dataclass
+class FileMetrics:
+    file: str
+    total: int
+    logic: int
+    comment: int
+    blank: int
+    string_literal: int
+
+    @property
+    def logic_pct(self) -> float:
+        return (self.logic / self.total * 100) if self.total else 0.0
+
+
+def analyze_file(path: str) -> FileMetrics:
+    """Count line types in a Rust source file."""
+    with open(path) as f:
+        lines = f.readlines()
+
+    total = len(lines)
+    blank = 0
+    comment = 0
+    string_lit = 0
+    logic = 0
+
+    in_block_comment = False
+    in_raw_string = False
+
+    for line in lines:
+        stripped = line.strip()
+
+        if not stripped:
+            blank += 1
+            continue
+
+        # Track block comments
+        if in_block_comment:
+            comment += 1
+            if '*/' in stripped:
+                in_block_comment = False
+            continue
+
+        if stripped.startswith('/*'):
+            comment += 1
+            if '*/' not in stripped:
+                in_block_comment = True
+            continue
+
+        # Line comments
+        if stripped.startswith('//'):
+            comment += 1
+            continue
+
+        # Raw string literals (r#"..."#, r##"..."##, etc.) and regular strings
+        # Heuristic: line is predominantly a string if it's inside a raw string
+        # or contains a long string literal (>60 chars of quoted content)
+        if in_raw_string:
+            string_lit += 1
+            if '"#' in stripped or '"##' in stripped:
+                in_raw_string = False
+            continue
+
+        if 'r#"' in stripped or 'r##"' in stripped:
+            if '"#' not in stripped.split('r#"', 1)[-1] if 'r#"' in stripped else True:
+                in_raw_string = True
+                string_lit += 1
+                continue
+
+        # Heuristic: if the line has a long string literal, count it
+        string_content = re.findall(r'"([^"]*)"', stripped)
+        total_string_chars = sum(len(s) for s in string_content)
+        if total_string_chars > 60:
+            string_lit += 1
+        else:
+            logic += 1
+
+    return FileMetrics(
+        file=path,
+        total=total,
+        logic=logic,
+        comment=comment,
+        blank=blank,
+        string_literal=string_lit,
+    )
+
+
+def collect_files(path: str) -> list[str]:
+    """Collect .rs files from a path (file or directory)."""
+    p = Path(path)
+    if p.is_file():
+        return [str(p)]
+    elif p.is_dir():
+        return sorted(str(f) for f in p.rglob('*.rs'))
+    else:
+        print(f"Error: {path} is not a file or directory", file=sys.stderr)
+        sys.exit(1)
+
+
+def main():
+    parser = argparse.ArgumentParser(description='Rust LOC breakdown analyzer')
+    parser.add_argument('paths', nargs='+', help='Rust source files or directories')
+    parser.add_argument('--json', action='store_true', help='Output as JSON')
+    parser.add_argument('--sort-by', choices=['total', 'logic', 'comment', 'string_literal'],
+                       default='total', help='Sort column')
+    args = parser.parse_args()
+
+    all_metrics: list[FileMetrics] = []
+    for path in args.paths:
+        for file in collect_files(path):
+            all_metrics.extend([analyze_file(file)])
+
+    all_metrics.sort(key=lambda m: getattr(m, args.sort_by), reverse=True)
+
+    if args.json:
+        print(json.dumps([asdict(m) for m in all_metrics], indent=2))
+    else:
+        # Summary
+        totals = FileMetrics(
+            file="TOTAL",
+            total=sum(m.total for m in all_metrics),
+            logic=sum(m.logic for m in all_metrics),
+            comment=sum(m.comment for m in all_metrics),
+            blank=sum(m.blank for m in all_metrics),
+            string_literal=sum(m.string_literal for m in all_metrics),
+        )
+
+        print(f"Files: {len(all_metrics)}, Total: {totals.total}, "
+              f"Logic: {totals.logic} ({totals.logic_pct:.1f}%), "
+              f"Comment: {totals.comment}, Blank: {totals.blank}, "
+              f"Strings: {totals.string_literal}")
+        print()
+
+        print(f"{'Total':>6}  {'Logic':>6}  {'Cmt':>5}  {'Blank':>5}  {'Str':>5}  {'%Logic':>6}  {'File'}")
+        print(f"{'─'*6}  {'─'*6}  {'─'*5}  {'─'*5}  {'─'*5}  {'─'*6}  {'─'*45}")
+        for m in all_metrics:
+            print(f"{m.total:>6}  {m.logic:>6}  {m.comment:>5}  {m.blank:>5}  "
+                  f"{m.string_literal:>5}  {m.logic_pct:>5.1f}%  {m.file}")
+        print(f"{'─'*6}  {'─'*6}  {'─'*5}  {'─'*5}  {'─'*5}  {'─'*6}  {'─'*45}")
+        print(f"{totals.total:>6}  {totals.logic:>6}  {totals.comment:>5}  {totals.blank:>5}  "
+              f"{totals.string_literal:>5}  {totals.logic_pct:>5.1f}%  TOTAL")
+
+
+if __name__ == '__main__':
+    main()