prompt-logger by alexniklev - MCP Server

Prompt Logger — MCP Server

A minimal Model Context Protocol (MCP) server that lets MCP‑aware clients (e.g. VS Code Copilot Chat with MCP support) persist prompts into a Git repository as Markdown files (with YAML frontmatter). Each save creates a new file, commits it, and pushes to the configured remote.

Current scope: a single tool (SavePrompt). Retrieval / listing are stubs or future roadmap items.

Why

Capture interesting prompts / conversations as immutable, versioned artifacts in a normal Git workflow so they can be:

Audited (history, diffs)
Reviewed and tagged
Reused across sessions / team members
Processed by other automation (indexing, analytics, embedding pipelines)

Features (Implemented Now)

Save a prompt into a Git repository (local + push)
Automatic filename generation with timestamp + slug
YAML frontmatter with created_at (UTC ISO 8601)
Minimal, dependency‑light code path
Runs over MCP stdio transport

Roadmap / Planned

Add metadata injection (author, tags, model, session id)
Optional delayed push (toggle immediate push vs local only)
List / search prompts tool
Get single prompt tool (actual file read)
Size limits (MAX_PROMPT_SIZE)
Git author identity env vars
Optional branch targeting
Robust error surface (JSON structured tool output)

File Layout

Saved prompt example (generated by the current implementation):

---
created_at: 2025-01-05T14:22:33.1234567Z
---

What is the weather in Sofia tomorrow?

Filename Format

prompt-YYYYMMDD_HHmms-<optional-slug>.md

YYYYMMDD_HHmms = UTC timestamp (sortable, millisecond precision)
<optional-slug> = first non-empty line of the prompt, lower‑cased, trimmed, sanitized (alphanumerics + - / _, max 40 chars)
Example: prompt-20250105_142233512-what-is-the-weather-in-sofia.md

Tools Exposed (MCP)

Tool	Description	Parameters
`SavePrompt`	Saves a prompt text to the repo, commits, pushes. Returns path + commit info (commit SHA placeholder today).	`prompt` (string, required)
`GetPrompt`	Placeholder (returns a stub string).	`prompt` (string)

SavePrompt Return Shape (current string form)

Saved: prompts/prompt-20250105_142233512-example.md
Commit: committed
Pushed: True

If it fails:

Error: <reason>

(Planned: return structured JSON via the tool API.)

Environment Variables (Currently Supported)

Variable	Purpose	Default
`REPO_PATH`	Path to an existing Git working copy to write into.	Current working directory
`PROMPTS_FOLDER`	Directory (relative to repo root) to store prompt files.	`prompts`

Other variables mentioned in the roadmap (author identity, push control, size limits) are not implemented yet and intentionally omitted here.

Git Remote / Auth

The code assumes the repo at REPO_PATH already has a configured remote and appropriate credentials available to git (SSH agent, credential manager, etc.). It simply runs:

git pull
git add <file>
git commit -m "Add prompt <filename>"
git push

Quick Start

Prepare a Git repo (existing or new):

git init prompt-archive
cd prompt-archive
git remote add origin <your-remote>
git pull origin main || true

Clone this project (or add as a tool service in your workspace).

(Optional) set environment variables:

set REPO_PATH=path\to\prompt-archive
set PROMPTS_FOLDER=prompts

Run the MCP server:

dotnet run --project src/PromptLoggerMcpServer

Configure .vscode/mcp.json (VS Code with MCP support):

{
  "servers": {
    "PromptLoggerMcpServer": {
      "type": "stdio",
      "command": "dotnet",
      "args": [
        "run",
        "--project",
        "src/PromptLoggerMcpServer"
      ],
      "env": {
        "REPO_PATH": "C:/dev/prompt-archive"
      }
    }
  }
}

In Copilot Chat (or another MCP client), invoke the tool:

/tool PromptLoggerMcpServer.SavePrompt prompt="What is the weather in Sofia tomorrow?"

Inspect the repo:
```
git log --oneline -1
ls prompts/
```

Error Handling

Typical failure causes:

REPO_PATH not a Git repo (missing .git directory)
Empty prompt text
Git command failure (network / auth / non-fast-forward)

Errors are returned as a simple string beginning with Error:.

Limitations / Caveats

Always pushes immediately (cannot opt out yet)
No structured JSON response
No deduplication / hashing (each call = new file)
No metadata enrichment beyond timestamp
GetPrompt is a stub
No concurrency coordination (simultaneous writes may race but filenames use millisecond precision; still possible under extreme parallelism)

Release Notes

1.0.0 (Initial)

Initial MCP server scaffolding
SavePrompt tool with git pull/add/commit/push workflow
Timestamp + slug filename strategy
YAML frontmatter with created_at
Basic error messages
Stub GetPrompt tool

Development

dotnet build
dotnet run --project src/PromptLoggerMcpServer

Contributing

Issues / PRs welcome. Focus areas: metadata, retrieval tooling, structured output, tests.

License

MIT (see LICENSE if present; otherwise add one before public distribution).

References

Model Context Protocol: https://modelcontextprotocol.io/
Protocol Spec: https://spec.modelcontextprotocol.io/
VS Code MCP Servers Guide: https://code.visualstudio.com/docs/copilot/chat/mcp-servers
NuGet MCP Guide: https://aka.ms/nuget/mcp/guide

Future improvements will be tracked in the issue tracker. Suggestions welcome.