diff --git a/packages/opencode/test/altimate/connections.test.ts b/packages/opencode/test/altimate/connections.test.ts
index e5facc6db..369f38893 100644
--- a/packages/opencode/test/altimate/connections.test.ts
+++ b/packages/opencode/test/altimate/connections.test.ts
@@ -261,6 +261,124 @@ snow:
       fs.rmSync(tmpDir, { recursive: true })
     }
   })
+
+  // altimate_change start — tests for untested dbt profiles parser edge cases
+  test("resolves env_var with default fallback when env var is missing", async () => {
+    const fs = await import("fs")
+    const os = await import("os")
+    const path = await import("path")
+
+    // Ensure the env var does NOT exist
+    delete process.env.__TEST_DBT_MISSING_VAR_12345
+
+    const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), "dbt-test-"))
+    const profilesPath = path.join(tmpDir, "profiles.yml")
+
+    fs.writeFileSync(
+      profilesPath,
+      `
+myproject:
+  outputs:
+    dev:
+      type: postgres
+      host: "{{ env_var('__TEST_DBT_MISSING_VAR_12345', 'localhost') }}"
+      port: 5432
+      user: "{{ env_var('__TEST_DBT_MISSING_USER_12345', 'default_user') }}"
+      password: secret
+      dbname: mydb
+`,
+    )
+
+    try {
+      const connections = await parseDbtProfiles(profilesPath)
+      expect(connections).toHaveLength(1)
+      expect(connections[0].config.host).toBe("localhost")
+      expect(connections[0].config.user).toBe("default_user")
+    } finally {
+      fs.rmSync(tmpDir, { recursive: true })
+    }
+  })
+
+  test("skips 'config' top-level key (dbt global settings)", async () => {
+    const fs = await import("fs")
+    const os = await import("os")
+    const path = await import("path")
+
+    const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), "dbt-test-"))
+    const profilesPath = path.join(tmpDir, "profiles.yml")
+
+    fs.writeFileSync(
+      profilesPath,
+      `
+config:
+  send_anonymous_usage_stats: false
+  use_colors: true
+
+real_project:
+  outputs:
+    dev:
+      type: postgres
+      host: localhost
+      dbname: analytics
+`,
+    )
+
+    try {
+      const connections = await parseDbtProfiles(profilesPath)
+      expect(connections).toHaveLength(1)
+      expect(connections[0].name).toBe("real_project_dev")
+      // The 'config' key should not appear as a connection
+      expect(connections.find((c) => c.name.startsWith("config"))).toBeUndefined()
+    } finally {
+      fs.rmSync(tmpDir, { recursive: true })
+    }
+  })
+
+  test("handles multiple profiles with multiple outputs", async () => {
+    const fs = await import("fs")
+    const os = await import("os")
+    const path = await import("path")
+
+    const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), "dbt-test-"))
+    const profilesPath = path.join(tmpDir, "profiles.yml")
+
+    fs.writeFileSync(
+      profilesPath,
+      `
+warehouse_a:
+  outputs:
+    dev:
+      type: postgres
+      host: localhost
+      dbname: dev_db
+    prod:
+      type: postgres
+      host: prod.example.com
+      dbname: prod_db
+
+warehouse_b:
+  outputs:
+    staging:
+      type: snowflake
+      account: abc123
+      user: admin
+      password: pw
+      database: STAGING
+      warehouse: COMPUTE_WH
+      schema: PUBLIC
+`,
+    )
+
+    try {
+      const connections = await parseDbtProfiles(profilesPath)
+      expect(connections).toHaveLength(3)
+      const names = connections.map((c) => c.name).sort()
+      expect(names).toEqual(["warehouse_a_dev", "warehouse_a_prod", "warehouse_b_staging"])
+    } finally {
+      fs.rmSync(tmpDir, { recursive: true })
+    }
+  })
+  // altimate_change end
 })
 
 // ---------------------------------------------------------------------------
diff --git a/packages/opencode/test/bus/bus-event.test.ts b/packages/opencode/test/bus/bus-event.test.ts
new file mode 100644
index 000000000..a18d19938
--- /dev/null
+++ b/packages/opencode/test/bus/bus-event.test.ts
@@ -0,0 +1,76 @@
+// altimate_change start — tests for BusEvent registry and payloads
+import { describe, test, expect } from "bun:test"
+import z from "zod"
+import { BusEvent } from "../../src/bus/bus-event"
+
+// Use unique type strings prefixed with __test_ to avoid colliding with
+// production events already registered in the global BusEvent registry.
+
+describe("BusEvent.define", () => {
+  test("returns an object with type string and zod schema", () => {
+    const schema = z.object({ count: z.number() })
+    const def = BusEvent.define("__test_define_shape", schema)
+
+    expect(def.type).toBe("__test_define_shape")
+    expect(def.properties).toBe(schema)
+  })
+})
+
+describe("BusEvent.payloads", () => {
+  // Register a known test event before payloads() tests
+  const testSchema = z.object({ value: z.string() })
+  BusEvent.define("__test_payloads_registered", testSchema)
+
+  test("includes a registered event in the discriminated union", () => {
+    const union = BusEvent.payloads()
+    const result = union.safeParse({
+      type: "__test_payloads_registered",
+      properties: { value: "hello" },
+    })
+    expect(result.success).toBe(true)
+  })
+
+  test("rejects event with unregistered type", () => {
+    const union = BusEvent.payloads()
+    const result = union.safeParse({
+      type: "__test_payloads_NONEXISTENT_999",
+      properties: {},
+    })
+    expect(result.success).toBe(false)
+  })
+
+  test("rejects event with wrong properties shape", () => {
+    const union = BusEvent.payloads()
+    const result = union.safeParse({
+      type: "__test_payloads_registered",
+      properties: { value: 42 }, // should be string, not number
+    })
+    expect(result.success).toBe(false)
+  })
+})
+
+describe("BusEvent.define duplicate handling", () => {
+  test("last define() wins when same type is registered twice", () => {
+    // First definition: requires { a: string }
+    BusEvent.define("__test_duplicate_overwrite", z.object({ a: z.string() }))
+    // Second definition: requires { b: number }
+    BusEvent.define("__test_duplicate_overwrite", z.object({ b: z.number() }))
+
+    const union = BusEvent.payloads()
+
+    // Payload matching second schema should succeed
+    const valid = union.safeParse({
+      type: "__test_duplicate_overwrite",
+      properties: { b: 42 },
+    })
+    expect(valid.success).toBe(true)
+
+    // Payload matching ONLY first schema (missing b) should fail
+    const invalid = union.safeParse({
+      type: "__test_duplicate_overwrite",
+      properties: { a: "hello" },
+    })
+    expect(invalid.success).toBe(false)
+  })
+})
+// altimate_change end