knoopx/tree-zipper
agent/skills/knowledge/tree-zipper/SKILL.md
Navigate immutable trees with a zipper cursor. Use when implementing tree traversal, editing tree structures functionally, or tracking focus through breadcrumbs.
$ install --global
skillsauthnpx skillsauth add knoopx/pi tree-zipperInstall this skill globally with one command. Works with Claude Code, Cursor, and Windsurf.
Security Scan Results
3 of 9 scanners reported clean
Some scanners were skipped, did not run, or reported a non-clean status. Review each row below.
3
Scanners Passed
9
Scanners in report
Clean
TrivyContainer and dependency vulnerability scanner
95%
Clean
SemgrepStatic code analysis for vulnerabilities
95%
Clean
mcp-scan (Snyk)Model Context Protocol security validation
95%
Skipped
Snyk (dep)Open source security scanning
50%
Skipped
Socket.devSupply chain security analysis
50%
Skipped
VirusTotalMulti-engine malware detection
50%
Skipped
CrowdStrikeAdvanced threat intelligence
50%
Skipped
OSV-ScannerOpen Source Vulnerability database check
50%
Skipped
OWASP Dep-Check
50%
Last scanned: May 18, 2026, 6:39 AM150.1s1 file scanned
SKILL.md
- name:
- tree-zipper
- description:
- Navigate immutable trees with a zipper cursor. Use when implementing tree traversal, editing tree structures functionally, or tracking focus through breadcrumbs.
- topic:
- Functional Tree Navigation
- token_cost:
- 130
- related:
- [tree-rerooting, dfs-vs-bfs]
When to use
A tree zipper is a cursor for immutable trees. State = (focus, trail).
Rules
- focus is the current subtree
- trail is a list of "breadcrumbs" describing the path from root to focus
- Each crumb remembers the parent's value plus the siblings NOT taken
- down_left/down_right push a crumb and make the chosen child the new focus
- up pops the top crumb, rebuilds the parent, and makes that parent the new focus
- set_value replaces the focused subtree's value
- to_tree walks all the way up to rebuild the whole tree
- Key invariant: you can ALWAYS reconstruct the full original tree from (focus, trail)
- Equality of two zippers = equality of the fully-reconstructed trees, NOT of the raw (focus, trail) pairs
- NEVER compare raw (focus, trail) pairs for equality
Operations
down_left, down_right, up, set_value, to_tree.
Example
Navigate: z.down_left() pushes a crumb (parent value + right siblings), sets focus to left child. z.up() pops crumb, rebuilds parent. z.to_tree() walks all the way up. Compare zippers by to_tree() equality, never raw (focus, trail).
Related Skills
knoopx/notify
tools
VerifiedTrustedCommunity
Inform the user what is happening — skip passive lookups
52SKILL.mdUpdated May 20, 2026
knoopx/markdown-rendering
development
VerifiedTrustedCommunity
Renders markdown to self-contained HTML with a custom dark stylesheet and opens in browser. Use when previewing markdown documents, generating styled HTML from README or report files.
52SKILL.mdUpdated May 20, 2026
knoopx/jj-hunk
testing
VerifiedTrustedCommunity
Programmatic hunk selection for Jujutsu — split, commit, or squash specific hunks without interactive prompts. Use when making partial commits or selective squashes.
52SKILL.mdUpdated May 18, 2026
knoopx/jj-core
content-media
VerifiedTrustedCommunity
Manage version control with Jujutsu (jj) — no staging area, immediate changes, smart rebasing. Use when navigating history, squashing, or pushing to Git remotes.
52SKILL.mdUpdated May 18, 2026