Data Structure Protocol (DSP)

LLM coding agents lose context between tasks. On large codebases they spend most of their tokens on "orientation" — figuring out where things live, what depends on what, and what is safe to change. DSP solves this by externalizing the project's structural map into a persistent, queryable graph stored in a .dsp/ directory next to the code.

DSP is NOT documentation for humans and NOT an AST dump. It captures three things: meaning (why an entity exists), boundaries (what it imports and exposes), and reasons (why each connection exists). This is enough for an agent to navigate, refactor, and generate code without loading the entire source tree into the context window.

When to Use

Use this skill when:

• The project has a .dsp/ directory (DSP is already set up)
• The user asks to set up DSP, bootstrap, or map a project's structure
• Creating, modifying, or deleting code files in a DSP-tracked project (to keep the graph updated)
• Navigating project structure, understanding dependencies, or finding specific modules
• The user mentions DSP, dsp-cli, .dsp, or structure mapping
• Performing impact analysis before a refactor or dependency replacement

Core Concepts

Code = graph

DSP models the codebase as a directed graph. Nodes are entities, edges are imports and shared/exports.

Two entity kinds exist:

• Object: any "thing" that isn't a function (module/file/class/config/resource/external dependency)
• Function: an exported function/method/handler/pipeline

Identity by UID, not by file path

Every entity gets a stable UID: obj-<8hex> for objects, func-<8hex> for functions. File paths are attributes that can change; UIDs survive renames, moves, and reformatting.

For entities inside a file, the UID is anchored with a comment marker in source code:

// @dsp func-7f3a9c12
export function calculateTotal(items) { ... }

# @dsp obj-e5f6g7h8
class UserService:

Every connection has a "why"

When an import is recorded, DSP stores a short reason explaining why that dependency exists. This lives in the exports/ reverse index of the imported entity. A dependency graph without reasons tells you what imports what; reasons tell you what is safe to change and who will break.

Storage format

Each entity gets a small directory under .dsp/:

.dsp/
├── TOC                        # ordered list of all entity UIDs from root
├── obj-a1b2c3d4/
│   ├── description            # source path, kind, purpose (1-3 sentences)
│   ├── imports                # UIDs this entity depends on (one per line)
│   ├── shared                 # UIDs of public API / exported entities
│   └── exports/               # reverse index: who imports this and why
│       ├── <importer_uid>     # file content = "why" text
│       └── <shared_uid>/
│           ├── description    # what is exported
│           └── <importer_uid> # why this specific export is imported
└── func-7f3a9c12/
    ├── description
    ├── imports
    └── exports/

Everything is plain text. Diffable. Reviewable. No database needed.

Full import coverage

Every file or artifact that is imported anywhere must be represented in .dsp as an Object — code, images, styles, configs, JSON, wasm, everything. External dependencies (npm packages, stdlib, etc.) are recorded as kind: external but their internals are never analyzed.

How It Works

Initial Setup

The skill relies on a standalone Python CLI script dsp-cli.py. If it is missing from the project, download it:

curl -O https://raw.githubusercontent.com/k-kolomeitsev/data-structure-protocol/main/skills/data-structure-protocol/scripts/dsp-cli.py

Requires Python 3.10+. All commands use python dsp-cli.py --root <project-root> <command>.

Bootstrap (initial mapping)

If .dsp/ is empty, traverse the project from root entrypoint(s) via DFS on imports:

1. Identify root entrypoints (package.json main, framework entry, main.py, etc.)
2. Document the root file: create-object, create-function for each export, create-shared, add-import for all dependencies
3. Take the first non-external import, document it fully, descend into its imports
4. Backtrack when no unvisited local imports remain; continue until all reachable files are documented
5. External dependencies: create-object --kind external, add to TOC, but never descend into node_modules/site-packages/etc.

Workflow Rules

• Before changing code: Find affected entities via search, find-by-source, or read-toc. Read their description and imports to understand context.
• When creating a file/module: Call create-object. For each exported function — create-function (with --owner). Register exports via create-shared.
• When adding an import: Call add-import with a brief why. For external deps — first create-object --kind external if the entity doesn't exist.
• When removing import/export/file: Call remove-import, remove-shared, remove-entity. Cascade cleanup is automatic.
• When renaming/moving a file: Call move-entity. UID does not change.
• Don't touch DSP if only internal implementation changed without affecting purpose or dependencies.

Key Commands

When to Update DSP

Examples

Example 1: Setting up DSP and documenting a module

python dsp-cli.py --root . init

python dsp-cli.py --root . create-object "src/app.ts" "Main application entrypoint"
# Output: obj-a1b2c3d4

python dsp-cli.py --root . create-function "src/app.ts#start" "Starts the HTTP server" --owner obj-a1b2c3d4
# Output: func-7f3a9c12

python dsp-cli.py --root . create-shared obj-a1b2c3d4 func-7f3a9c12

python dsp-cli.py --root . add-import obj-a1b2c3d4 obj-deadbeef "HTTP routing"

Example 2: Navigating the graph before making changes

python dsp-cli.py --root . search "authentication"
python dsp-cli.py --root . get-entity obj-a1b2c3d4
python dsp-cli.py --root . get-children obj-a1b2c3d4 --depth 2
python dsp-cli.py --root . get-recipients obj-a1b2c3d4
python dsp-cli.py --root . get-path obj-a1b2c3d4 func-7f3a9c12

Example 3: Impact analysis before replacing a library

python dsp-cli.py --root . find-by-source "lodash"
# Output: obj-11223344

python dsp-cli.py --root . get-recipients obj-11223344
# Shows every module that imports lodash and WHY — lets you systematically replace it

Best Practices

• ✅ Do: Update DSP immediately when creating new files, adding imports, or changing public APIs
• ✅ Do: Always add a meaningful why reason when recording an import — this is where most of DSP's value lives
• ✅ Do: Use kind: external for third-party libraries without analyzing their internals
• ✅ Do: Keep descriptions minimal (1-3 sentences about purpose, not implementation)
• ✅ Do: Treat .dsp/ diffs like code diffs — review them, keep them accurate
• ❌ Don't: Touch .dsp/ for internal-only changes that don't affect purpose or dependencies
• ❌ Don't: Change an entity's UID on rename/move (use move-entity instead)
• ❌ Don't: Create UIDs for every local variable or helper — only file-level Objects and public/shared entities

Integration

This skill connects naturally to:

• context-compression — DSP reduces the need for compression by providing targeted retrieval instead of loading everything
• context-optimization — DSP is a structural optimization: agents pull minimal "context bundles" instead of raw source
• architecture — DSP captures architectural boundaries (imports/exports) that feed system design decisions

References

• Full architecture specification: ARCHITECTURE.md
• CLI source + reference docs: skills/data-structure-protocol
• Introduction article: article.md