diff --git a/packages/opencode/test/altimate/connection-registry.test.ts b/packages/opencode/test/altimate/connection-registry.test.ts
new file mode 100644
index 000000000..dc1ba9f12
--- /dev/null
+++ b/packages/opencode/test/altimate/connection-registry.test.ts
@@ -0,0 +1,170 @@
+// altimate_change start — unit tests for connection registry pure functions
+import { describe, test, expect, beforeEach, afterEach } from "bun:test"
+import {
+  detectAuthMethod,
+  categorizeConnectionError,
+  reset,
+  load,
+  getConfig,
+  list,
+  setConfigs,
+} from "../../src/altimate/native/connections/registry"
+
+// ---------------------------------------------------------------------------
+// 1. detectAuthMethod — MongoDB paths (added in #482, zero coverage)
+// ---------------------------------------------------------------------------
+
+describe("detectAuthMethod: MongoDB", () => {
+  test('returns "password" when mongodb config has a password', () => {
+    // Note: this actually hits the generic `config.password` check (line 226)
+    // before the MongoDB-specific branch, but the behavior is still correct
+    // and worth pinning.
+    expect(detectAuthMethod({ type: "mongodb", password: "secret" })).toBe("password")
+  })
+
+  test('returns "connection_string" when mongodb config has no password', () => {
+    // This is the MongoDB-specific branch at line 229 of registry.ts
+    expect(detectAuthMethod({ type: "mongodb" })).toBe("connection_string")
+  })
+
+  test('returns "connection_string" when mongo (alias) has no password', () => {
+    expect(detectAuthMethod({ type: "mongo" })).toBe("connection_string")
+  })
+
+  test('returns "password" when mongo (alias) has a password', () => {
+    expect(detectAuthMethod({ type: "mongo", password: "secret" })).toBe("password")
+  })
+
+  test('returns "connection_string" when mongodb has connection_string field', () => {
+    // connection_string check (line 216) fires BEFORE the type check,
+    // so this should return "connection_string" — verify the priority is correct
+    expect(detectAuthMethod({ type: "mongodb", connection_string: "mongodb://localhost" })).toBe("connection_string")
+  })
+
+  test('returns "token" when mongodb has access_token', () => {
+    // Token check fires before MongoDB type check
+    expect(detectAuthMethod({ type: "mongodb", access_token: "tok" })).toBe("token")
+  })
+})
+
+// ---------------------------------------------------------------------------
+// 2. loadFromEnv via public API (reset + load + getConfig)
+// ---------------------------------------------------------------------------
+
+describe("loadFromEnv via public API", () => {
+  const envVars: string[] = []
+
+  function setEnv(key: string, value: string) {
+    process.env[key] = value
+    envVars.push(key)
+  }
+
+  beforeEach(() => {
+    reset()
+  })
+
+  afterEach(() => {
+    for (const key of envVars) {
+      delete process.env[key]
+    }
+    envVars.length = 0
+    reset()
+  })
+
+  test("parses valid ALTIMATE_CODE_CONN_* env var into a connection config", () => {
+    setEnv("ALTIMATE_CODE_CONN_MYDB", JSON.stringify({ type: "postgres", host: "localhost", port: 5432 }))
+    load()
+    const config = getConfig("mydb")
+    expect(config).toBeDefined()
+    expect(config!.type).toBe("postgres")
+    expect(config!.host).toBe("localhost")
+  })
+
+  test("lowercases the connection name from env var suffix", () => {
+    setEnv("ALTIMATE_CODE_CONN_MYUPPERDB", JSON.stringify({ type: "postgres" }))
+    load()
+    // The name should be lowercased
+    expect(getConfig("myupperdb")).toBeDefined()
+    // Original case should not exist as a separate entry
+    expect(getConfig("MYUPPERDB")).toBeUndefined()
+  })
+
+  test("ignores env var with malformed JSON", () => {
+    setEnv("ALTIMATE_CODE_CONN_BAD", "not valid json {{{")
+    load()
+    expect(getConfig("bad")).toBeUndefined()
+  })
+
+  test("ignores env var with missing type field", () => {
+    setEnv("ALTIMATE_CODE_CONN_NOTYPE", JSON.stringify({ host: "localhost" }))
+    load()
+    expect(getConfig("notype")).toBeUndefined()
+  })
+
+  test("ignores env var with null JSON value", () => {
+    setEnv("ALTIMATE_CODE_CONN_NULLVAL", "null")
+    load()
+    expect(getConfig("nullval")).toBeUndefined()
+  })
+
+  test("ignores env var with empty string value", () => {
+    // Empty string is falsy, so the `if (!value) continue` guard should skip it
+    process.env["ALTIMATE_CODE_CONN_EMPTY"] = ""
+    envVars.push("ALTIMATE_CODE_CONN_EMPTY")
+    load()
+    expect(getConfig("empty")).toBeUndefined()
+  })
+
+  test("env vars are included in list() output", () => {
+    setEnv("ALTIMATE_CODE_CONN_ENVDB", JSON.stringify({ type: "duckdb", database: "test.db" }))
+    load()
+    const { warehouses } = list()
+    const found = warehouses.find((w) => w.name === "envdb")
+    expect(found).toBeDefined()
+    expect(found!.type).toBe("duckdb")
+  })
+})
+
+// ---------------------------------------------------------------------------
+// 3. setConfigs + list round-trip (public API sanity)
+// ---------------------------------------------------------------------------
+
+describe("setConfigs and list", () => {
+  beforeEach(() => {
+    reset()
+  })
+
+  afterEach(() => {
+    reset()
+  })
+
+  test("setConfigs populates configs readable via getConfig", () => {
+    setConfigs({
+      prod: { type: "postgres", host: "prod.example.com" },
+      staging: { type: "snowflake", account: "acme" },
+    })
+    expect(getConfig("prod")).toBeDefined()
+    expect(getConfig("prod")!.type).toBe("postgres")
+    expect(getConfig("staging")).toBeDefined()
+    expect(getConfig("staging")!.type).toBe("snowflake")
+  })
+
+  test("list returns all configured warehouses", () => {
+    setConfigs({
+      a: { type: "postgres" },
+      b: { type: "mongodb", database: "mydb" },
+    })
+    const { warehouses } = list()
+    expect(warehouses).toHaveLength(2)
+    const names = warehouses.map((w) => w.name).sort()
+    expect(names).toEqual(["a", "b"])
+  })
+
+  test("setConfigs clears previous configs", () => {
+    setConfigs({ old: { type: "postgres" } })
+    setConfigs({ new: { type: "duckdb" } })
+    expect(getConfig("old")).toBeUndefined()
+    expect(getConfig("new")).toBeDefined()
+  })
+})
+// altimate_change end