Foundry Adapter

Unofficial local HTTP simulation of selected Palantir Foundry API v2 ontology-read operations, shipped as the independently versioned semblance-foundry package.

This adapter is not affiliated with, endorsed by, or equivalent to Palantir. It does not implement Foundry's ontology engine, permissions, or compute. It is a test double for client development and CI.

Install it separately from core Semblance:

pip install semblance-foundry

Requires semblance 0.8.x or 0.9.x. Verified against public API v2 documentation dated 2026-08-18.

Quick start

from semblance_foundry import FoundryMock, FoundryMockConfig
from semblance_foundry.testing import foundry_test_client

foundry = FoundryMock(FoundryMockConfig(seed=42, auth="optional"))
foundry.load_bundled_fixture()
client = foundry_test_client(foundry)

r = client.get("/api/v2/ontologies/acme/objects/Employee?pageSize=2")
assert r.status_code == 200

load_bundled_fixture() loads the shipped acme ontology. Use load_fixture(path) for your own YAML or JSON.

CLI:

semblance-foundry fixture init --output foundry.yaml
semblance-foundry validate foundry.yaml
semblance-foundry operations
semblance-foundry serve --fixture foundry.yaml --port 8765

Omitting --fixture serves the bundled acme example.

Auth modes

disabled — ignore Authorization
optional (default) — missing token is OK; malformed Bearer values return 401
strict — token must be in FoundryMockConfig.tokens

Authentication errors never echo the token. This is not an OAuth server and does not validate real Palantir credentials.

What 0.1.0 covers

Level	Operations
exact	list/get ontologies, object types, objects, linked objects, action types (metadata), query types
representative	object search (`eq` / `and` of `eq` only), query execute (static fixture or allow-listed Python callback)
unsupported	apply, applyBatch

Unknown paths return a Foundry-style 404. Apply / applyBatch return 501 UnsupportedOperation only when auth=strict; otherwise 404.

Not in 0.1.0: aggregates, object sets, datasets, transactions, orchestration, streams.

The live compatibility table is also served at /.well-known/foundry-mock-compatibility.json.

Fixtures

YAML/JSON version 1. Extra fields are rejected. Fixtures are data only — no expressions are evaluated. Register query callbacks in Python:

foundry.register_query("employeesByOffice", lambda params, state: {"data": []})

Pagination

List endpoints use pageSize / pageToken / nextPageToken. Tokens are opaque and checksummed. Tampering or cross-resource reuse returns InvalidPageToken (400).

Testing with the official SDK

HTTP contract tests are the required surface. An optional extra pins foundry-platform-sdk==1.101.0 for localhost compatibility checks; untested SDK versions are not implied compatible.

pip install "semblance-foundry[sdk]"
pytest packages/semblance-foundry/tests -m sdk