Ship tastytrade-mcp as a plugin, with credentials in ~/.tastytrade-mcp

[walkerhughes]

Credentials now resolve from ~/.tastytrade-mcp/credentials.json, mirroring how the harbor CLI stores its key, and tastytrade-mcp installs as a plugin from this marketplace.

Credentials

New src/credentials.py. TastyTrade has no auth login equivalent, so the file is created by hand from a registered OAuth application; the README documents the shape and how to obtain each value.

Precedence is whole-source, not per-field: the environment when all three of TT_CLIENT_ID/TT_SECRET/TT_REFRESH are set, otherwise the file. Mixing a file client_id with an environment refresh_token would fail authentication in a way that looks like a revoked token rather than a misconfiguration.

A partially set environment is a hard error, not a silent fallthrough to the file. That fallthrough is invisible and the resulting 401 is actively misleading, which is the same shape of bug that cost real debugging time earlier in this repo's history.

The file is refused if group- or world-readable, with a chmod 600 remediation. The client secret and refresh token together grant full account access, including order placement when TT_ENABLE_TRADING=true.

client.py previously did os.environ["TT_CLIENT_ID"], so a missing credential raised a bare KeyError. Tests that pass all three explicitly still skip resolution entirely, so the mock-API suite needs no credentials or file.

Plugin

Manifest, marketplace entry, and scripts/start-server.sh reusing the launcher proven in #5: uv discovery across common install locations, VIRTUAL_ENV dropped, plugin root resolved from the script's own location, and a bare ${CLAUDE_PLUGIN_ROOT} with no :- default.

A packaging bug found along the way

The launcher cds into the project and runs python -m src.server rather than the tastytrade-mcp console script, because that script does not work:

Test on the built wheel	Result
import server	attempted relative import with no known parent package
import tools.options	attempted relative import beyond top-level package
tastytrade-mcp	ModuleNotFoundError: No module named 'src'
site-packages	receives a stray top-level __init__.py

sources = { "src" = "" } flattens the package while every internal import is relative, so an installed wheel cannot import itself. This is pre-existing and does not block the plugin; the launcher sets cwd explicitly, so the invocation is deterministic. Worth its own PR (move src/ to src/tastytrade_mcp/, which leaves all relative imports untouched).

Error handling

guarded_tool had no catch-all, so its docstring promise that a tool never hands back a traceback was false for anything outside four exception types. Added CredentialsError handling plus a last-resort Exception clause. With no credentials anywhere, a tool call now returns:

{
  "error": "No Tastytrade credentials found. Create /.../.tastytrade-mcp/credentials.json containing {\"client_id\": \"...\", \"client_secret\": \"...\", \"refresh_token\": \"...\"} with mode 600, or set TT_CLIENT_ID, TT_SECRET and TT_REFRESH.",
  "suggestions": ["See the tastytrade-mcp README for how to obtain each value."]
}

The 401 guidance named only the environment variables. It now explains that resolved-but-rejected means stale rather than missing, names both sources, and says not to ask the user to paste a secret into the chat.

CI

plugin-version now discovers every */.claude-plugin/plugin.json instead of hardcoding harbor-mcp, so a future plugin is gated without editing the workflow, and a brand-new manifest is skipped rather than failing. Verified locally against this branch: harbor skips (unchanged), tastytrade skips (new).

tests/unit/test_plugin_config.py mirrors harbor's guard: no :- default, launcher exists and is executable, no source .env, no credential named in the plugin config, semver version.

Verification

Check	Result
ruff check / format	clean
mypy	no issues, 29 files
Unit tests	90 passed
With integration	102 passed, 92.91% coverage (gate 80%)
Eval verifiers	12 passed, 0 failed
claude plugin validate	passes both manifests
Launcher from unrelated cwd	handshake OK, 12 tools
Launcher under env -i PATH=/usr/bin:/bin	handshake OK (the -32000 case)
No credentials anywhere	structured error, no traceback

The one validator warning is expected: CLAUDE.md at the plugin root is not loaded as project context. That file is development guidance for working on this subdirectory, which is where it belongs, and it is correctly not shipped as plugin context.