diff --git a/install.sh b/install.sh
index fce3f48..529a6e9 100755
--- a/install.sh
+++ b/install.sh
@@ -38,6 +38,7 @@ SKILLS=(
   "pst:patch"
   "pst:push"
   "pst:python-refactor"
+  "pst:refactor"
   "pst:quality-gates"
   "pst:qa"
   "pst:rebase"
diff --git a/skills/pst:refactor/SKILL.md b/skills/pst:refactor/SKILL.md
new file mode 100644
index 0000000..8200fc0
--- /dev/null
+++ b/skills/pst:refactor/SKILL.md
@@ -0,0 +1,125 @@
+---
+name: pst:refactor
+description: Comprehensive Fowler maintainability refactor pass across the entire codebase. An Opus background agent analyzes all code files against the 16-smell rubric in MAINTAINABILITY.md, produces a prioritized smell inventory, then parallel Sonnet agents fix each file in isolated worktrees (behavior-preserving, two hats per rule 15). Run any time you want human maintainability optimized across the board, independent of feature work.
+argument-hint: "[path-or-glob] [--report-only]"
+allowed-tools: Bash, Read, Edit, Write, Grep, Glob, Agent, AskUserQuestion
+---
+
+# /pst:refactor
+
+Comprehensive Fowler code-smell pass. Opus analyzes the full codebase (or a
+scoped path), Sonnet fixes each smell in an isolated worktree. Always the
+second hat -- behavior stays identical, only structure improves.
+
+## 1. Setup
+
+Resolve the MAINTAINABILITY.md rubric path at runtime:
+
+```sh
+LEDGER="$(cat ~/.claude/pst/ledger-path 2>/dev/null)"
+MAINT="$(dirname "$LEDGER")/../MAINTAINABILITY.md"
+cat "$MAINT"
+```
+
+Determine the scan root from `$ARGUMENTS`:
+
+- **Path or glob provided**: scan only that subtree.
+- **No argument**: scan the entire repo working tree.
+
+Discover all code files (exclude lockfiles, generated files, docs):
+
+```sh
+git ls-files | grep -Ev '\.(lock|snap|min\.(js|css)|pb\.go|pb_test\.go)$' \
+  | grep -Ev '^(docs?/|\.github/|dist/|build/)' \
+  | grep -E '\.(rb|py|ts|tsx|js|jsx|go|rs|java|kt|swift|ex|exs|cs|cpp|c|h)$'
+```
+
+## 2. Opus smell analysis (background)
+
+Spawn one background Opus agent (`model: opus`) with:
+
+- The full content of `MAINTAINABILITY.md` (read via the path resolved above).
+- The list of code files from step 1.
+- Read every file in the list.
+- Instruction:
+
+  ```
+  You are a maintainability auditor. For each file, identify which of the 16
+  canonical Fowler code smells are present. For every finding, record:
+    - file path and approximate line range
+    - smell name
+    - one-sentence description of the specific instance
+    - recommended refactoring (Extract Function, Move Method, etc.)
+
+  Rank findings by impact: smells that would most reduce future change cost
+  come first. Smells that require a behavior change to fix (e.g. API redesign
+  that breaks callers) are out of scope -- skip them.
+
+  Return a JSON array:
+  [
+    {
+      "file": "path/to/file.rb",
+      "smell": "Duplicated Code",
+      "lines": "42-61",
+      "detail": "Login and signup both inline-validate email format.",
+      "fix": "Extract Function: extract validate_email into a shared helper."
+    }
+  ]
+  ```
+
+## 3. Present findings and gate
+
+Group findings by file. Present as a summary table:
+
+```
+File                    Smells   Top smell
+src/auth/session.rb        3     Duplicated Code (lines 42-61)
+src/api/handler.ts         2     Long Function (lines 120-180)
+...
+```
+
+If no findings: report "No smells detected." and stop.
+
+If `--report-only` was passed, stop here.
+
+Use `AskUserQuestion`: **Apply all fixes in isolated worktrees?** (Yes / Report
+only). Treat no objection as Yes.
+
+## 4. Parallel Sonnet implementers (isolated worktrees)
+
+Group findings by file. Spawn one background Sonnet agent per file
+(`model: sonnet`, `isolation: worktree`) with:
+
+- The file content.
+- The smell findings for that file.
+- Instruction:
+
+  ```
+  Apply each refactoring listed below to this file. Rules:
+  - Behavior-preserving only. Do not change any observable behavior.
+  - Run existing tests if a test runner is available; skip any fix that
+    breaks a test and note it.
+  - After all fixes: stage the changed file and commit:
+      git add <file>
+      git commit -m "refactor(<file>): <primary smell fixed>"
+    Include the co-author trailer:
+      Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
+  - If no fix is safe to apply, commit nothing and return a skip reason.
+  ```
+
+## 5. Report
+
+After all worktree agents complete:
+
+- List each file: smells fixed, smells skipped (with reason), test result.
+- If any fix broke a test, name the fix and the failing test.
+- State total smells fixed vs. skipped.
+
+## Notes
+
+- Rule 15 two-hats: every commit from this skill is a pure refactor. If a
+  fix requires a behavior change, skip it and surface it as a follow-up.
+- Rule 7 applies if you intend to merge the result via PR: adversarial review
+  before merge.
+- For very large codebases (> 50 files), run with a scoped path first:
+  `/pst:refactor src/auth` then widen.