diff --git a/packages/opencode/src/file/ignore.ts b/packages/opencode/src/file/ignore.ts
index b9731040c7..4a7261ea85 100644
--- a/packages/opencode/src/file/ignore.ts
+++ b/packages/opencode/src/file/ignore.ts
@@ -31,6 +31,8 @@ export namespace FileIgnore {
     "mypy_cache",
     ".history",
     ".gradle",
+    "dbt_packages",
+    "dbt_modules",
   ])
 
   const FILES = [
diff --git a/packages/opencode/test/file/ignore.test.ts b/packages/opencode/test/file/ignore.test.ts
index ceab2a121c..a547eea145 100644
--- a/packages/opencode/test/file/ignore.test.ts
+++ b/packages/opencode/test/file/ignore.test.ts
@@ -52,3 +52,56 @@ describe("FileIgnore.match: directory and file patterns", () => {
     expect(FileIgnore.match("src\\.git\\config")).toBe(true)
   })
 })
+
+describe("FileIgnore.match: dbt directory patterns", () => {
+  test("matches dbt_packages directory and nested files", () => {
+    expect(FileIgnore.match("dbt_packages")).toBe(true)
+    expect(FileIgnore.match("dbt_packages/")).toBe(true)
+    expect(FileIgnore.match("dbt_packages/dbt_utils/macros/sql/generate_series.sql")).toBe(true)
+    expect(FileIgnore.match("dbt_packages/dbt_expectations/macros/schema_tests/expect_column_values_to_be_unique.sql")).toBe(true)
+    expect(FileIgnore.match("dbt_packages/some_package/models/staging/stg_orders.sql")).toBe(true)
+  })
+
+  test("matches dbt_modules directory and nested files", () => {
+    expect(FileIgnore.match("dbt_modules")).toBe(true)
+    expect(FileIgnore.match("dbt_modules/")).toBe(true)
+    expect(FileIgnore.match("dbt_modules/dbt_utils/macros/sql/generate_series.sql")).toBe(true)
+  })
+
+  test("matches dbt directories nested under project subdirectories", () => {
+    expect(FileIgnore.match("my_project/dbt_packages/dbt_utils/macros/sql/union.sql")).toBe(true)
+    expect(FileIgnore.match("my_project/dbt_modules/some_package/models/model.sql")).toBe(true)
+  })
+
+  test("matches dbt directories with Windows-style separators", () => {
+    expect(FileIgnore.match("dbt_packages\\dbt_utils\\macros\\generate_series.sql")).toBe(true)
+    expect(FileIgnore.match("dbt_modules\\some_package\\models\\model.sql")).toBe(true)
+  })
+
+  test("does not match files that merely contain dbt_packages in their name", () => {
+    expect(FileIgnore.match("setup_dbt_packages.sh")).toBe(false)
+    expect(FileIgnore.match("docs/dbt_packages_guide.md")).toBe(false)
+  })
+})
+
+describe("FileIgnore.PATTERNS: watcher ignore list", () => {
+  test("includes dbt_packages in PATTERNS array used by file watcher", () => {
+    expect(FileIgnore.PATTERNS).toContain("dbt_packages")
+  })
+
+  test("includes dbt_modules in PATTERNS array used by file watcher", () => {
+    expect(FileIgnore.PATTERNS).toContain("dbt_modules")
+  })
+
+  test("includes other expected dependency directories", () => {
+    expect(FileIgnore.PATTERNS).toContain("node_modules")
+    expect(FileIgnore.PATTERNS).toContain("vendor")
+    expect(FileIgnore.PATTERNS).toContain("bower_components")
+  })
+
+  test("includes build output directories", () => {
+    expect(FileIgnore.PATTERNS).toContain("dist")
+    expect(FileIgnore.PATTERNS).toContain("build")
+    expect(FileIgnore.PATTERNS).toContain("target")
+  })
+})
diff --git a/packages/opencode/test/file/watcher-ignore.test.ts b/packages/opencode/test/file/watcher-ignore.test.ts
new file mode 100644
index 0000000000..a6ef4aed73
--- /dev/null
+++ b/packages/opencode/test/file/watcher-ignore.test.ts
@@ -0,0 +1,247 @@
+import { describe, test, expect } from "bun:test"
+import path from "path"
+import fs from "fs/promises"
+import { Instance } from "../../src/project/instance"
+import { tmpdir } from "../fixture/fixture"
+import { FileIgnore } from "../../src/file/ignore"
+
+/**
+ * E2E tests for file watcher ignore patterns.
+ *
+ * These tests verify that the watcher's ignore list correctly excludes
+ * dbt dependency directories (dbt_packages, dbt_modules) which can contain
+ * thousands of files and exhaust macOS file descriptor limits (EMFILE).
+ *
+ * See: https://github.com/AltimateAI/altimate-code/issues/500
+ */
+
+describe("watcher ignore: dbt directories", () => {
+  test("dbt_packages is in FileIgnore.PATTERNS passed to the watcher", () => {
+    expect(FileIgnore.PATTERNS).toContain("dbt_packages")
+  })
+
+  test("dbt_modules is in FileIgnore.PATTERNS passed to the watcher", () => {
+    expect(FileIgnore.PATTERNS).toContain("dbt_modules")
+  })
+
+  test("FileIgnore.match ignores files inside dbt_packages at any depth", () => {
+    // Root level
+    expect(FileIgnore.match("dbt_packages")).toBe(true)
+    expect(FileIgnore.match("dbt_packages/")).toBe(true)
+
+    // Typical dbt package structure: macros, models, etc.
+    expect(FileIgnore.match("dbt_packages/dbt_utils/macros/sql/generate_series.sql")).toBe(true)
+    expect(FileIgnore.match("dbt_packages/dbt_utils/macros/sql/get_column_values.sql")).toBe(true)
+    expect(FileIgnore.match("dbt_packages/dbt_expectations/macros/schema_tests/expect_column_values_to_be_unique.sql")).toBe(true)
+    expect(FileIgnore.match("dbt_packages/codegen/macros/generate_source.sql")).toBe(true)
+
+    // Deeply nested
+    expect(FileIgnore.match("dbt_packages/pkg/a/b/c/d/e/model.sql")).toBe(true)
+  })
+
+  test("FileIgnore.match ignores files inside dbt_modules at any depth", () => {
+    expect(FileIgnore.match("dbt_modules")).toBe(true)
+    expect(FileIgnore.match("dbt_modules/")).toBe(true)
+    expect(FileIgnore.match("dbt_modules/dbt_utils/macros/sql/generate_series.sql")).toBe(true)
+    expect(FileIgnore.match("dbt_modules/pkg/a/b/c/model.sql")).toBe(true)
+  })
+
+  test("FileIgnore.match ignores dbt directories nested under project paths", () => {
+    expect(FileIgnore.match("my_dbt_project/dbt_packages/dbt_utils/macros/union.sql")).toBe(true)
+    expect(FileIgnore.match("projects/analytics/dbt_packages/pkg/model.sql")).toBe(true)
+    expect(FileIgnore.match("src/dbt_modules/old_pkg/macros/macro.sql")).toBe(true)
+  })
+
+  test("FileIgnore.match does not false-positive on files containing dbt_packages in name", () => {
+    // Files that have "dbt_packages" as part of their filename should NOT match
+    expect(FileIgnore.match("install_dbt_packages.sh")).toBe(false)
+    expect(FileIgnore.match("docs/about_dbt_packages.md")).toBe(false)
+    expect(FileIgnore.match("scripts/setup_dbt_packages.py")).toBe(false)
+    expect(FileIgnore.match("dbt_packages_list.txt")).toBe(false)
+  })
+
+  test("FileIgnore.match does not false-positive on files containing dbt_modules in name", () => {
+    expect(FileIgnore.match("install_dbt_modules.sh")).toBe(false)
+    expect(FileIgnore.match("dbt_modules_config.yml")).toBe(false)
+  })
+
+  test("whitelist can override dbt_packages ignore", () => {
+    expect(
+      FileIgnore.match("dbt_packages/custom_pkg/model.sql", {
+        whitelist: ["dbt_packages/**"],
+      }),
+    ).toBe(false)
+  })
+})
+
+describe("watcher ignore: dbt project simulation", () => {
+  test("watcher ignore list covers a realistic dbt project structure", async () => {
+    await using tmp = await tmpdir()
+
+    // Simulate a dbt project directory structure
+    const dirs = [
+      "models/staging",
+      "models/marts",
+      "macros",
+      "seeds",
+      "tests",
+      "snapshots",
+      "analyses",
+      // dbt dependencies - these should be ignored
+      "dbt_packages/dbt_utils/macros/sql",
+      "dbt_packages/dbt_utils/macros/cross_db_utils",
+      "dbt_packages/dbt_expectations/macros/schema_tests",
+      "dbt_packages/codegen/macros",
+      "dbt_packages/audit_helper/macros",
+      "dbt_modules/legacy_pkg/macros",
+      // Other dirs that should be ignored
+      "target/compiled/my_project/models",
+      "target/run/my_project/models",
+      "logs",
+      "node_modules/.cache",
+    ]
+
+    for (const dir of dirs) {
+      await fs.mkdir(path.join(tmp.path, dir), { recursive: true })
+    }
+
+    // Create files in each directory
+    const files = [
+      // User files - should NOT be ignored
+      "dbt_project.yml",
+      "packages.yml",
+      "models/staging/stg_orders.sql",
+      "models/marts/dim_customers.sql",
+      "macros/generate_schema_name.sql",
+      "seeds/country_codes.csv",
+      // dbt_packages files - SHOULD be ignored
+      "dbt_packages/dbt_utils/macros/sql/generate_series.sql",
+      "dbt_packages/dbt_utils/macros/sql/get_column_values.sql",
+      "dbt_packages/dbt_utils/macros/sql/pivot.sql",
+      "dbt_packages/dbt_utils/macros/sql/union.sql",
+      "dbt_packages/dbt_utils/macros/sql/star.sql",
+      "dbt_packages/dbt_utils/macros/cross_db_utils/dateadd.sql",
+      "dbt_packages/dbt_expectations/macros/schema_tests/expect_column_values_to_be_unique.sql",
+      "dbt_packages/codegen/macros/generate_source.sql",
+      "dbt_packages/audit_helper/macros/compare_relations.sql",
+      // dbt_modules files - SHOULD be ignored
+      "dbt_modules/legacy_pkg/macros/old_macro.sql",
+      // target files - SHOULD be ignored
+      "target/compiled/my_project/models/stg_orders.sql",
+      "target/run/my_project/models/stg_orders.sql",
+    ]
+
+    for (const file of files) {
+      await fs.writeFile(path.join(tmp.path, file), `-- ${file}`)
+    }
+
+    // Verify user project files are NOT ignored
+    const userFiles = [
+      "dbt_project.yml",
+      "packages.yml",
+      "models/staging/stg_orders.sql",
+      "models/marts/dim_customers.sql",
+      "macros/generate_schema_name.sql",
+      "seeds/country_codes.csv",
+    ]
+    for (const file of userFiles) {
+      expect(FileIgnore.match(file)).toBe(false)
+    }
+
+    // Verify dbt_packages files ARE ignored
+    const dbtPackageFiles = [
+      "dbt_packages/dbt_utils/macros/sql/generate_series.sql",
+      "dbt_packages/dbt_utils/macros/sql/get_column_values.sql",
+      "dbt_packages/dbt_utils/macros/sql/pivot.sql",
+      "dbt_packages/dbt_utils/macros/sql/union.sql",
+      "dbt_packages/dbt_utils/macros/sql/star.sql",
+      "dbt_packages/dbt_utils/macros/cross_db_utils/dateadd.sql",
+      "dbt_packages/dbt_expectations/macros/schema_tests/expect_column_values_to_be_unique.sql",
+      "dbt_packages/codegen/macros/generate_source.sql",
+      "dbt_packages/audit_helper/macros/compare_relations.sql",
+    ]
+    for (const file of dbtPackageFiles) {
+      expect(FileIgnore.match(file)).toBe(true)
+    }
+
+    // Verify dbt_modules files ARE ignored
+    expect(FileIgnore.match("dbt_modules/legacy_pkg/macros/old_macro.sql")).toBe(true)
+
+    // Verify target files ARE ignored
+    expect(FileIgnore.match("target/compiled/my_project/models/stg_orders.sql")).toBe(true)
+    expect(FileIgnore.match("target/run/my_project/models/stg_orders.sql")).toBe(true)
+  })
+
+  test("PATTERNS array has sufficient coverage for dbt ecosystem", () => {
+    // All dbt dependency directories should be in PATTERNS
+    expect(FileIgnore.PATTERNS).toContain("dbt_packages")
+    expect(FileIgnore.PATTERNS).toContain("dbt_modules")
+
+    // target/ (build artifacts) should also be covered
+    expect(FileIgnore.PATTERNS).toContain("target")
+
+    // logs/ should be covered by glob pattern
+    expect(FileIgnore.match("logs/dbt.log")).toBe(true)
+  })
+})
+
+describe("watcher ignore: file descriptor exhaustion prevention", () => {
+  test("simulated large dbt_packages tree is fully ignored", async () => {
+    // Simulate the scenario from issue #500: 443+ macro files
+    // Verify that ALL paths within dbt_packages would be ignored by the watcher
+    const packages = ["dbt_utils", "dbt_expectations", "codegen", "audit_helper", "dbt_date", "dbt_profiler"]
+    const subdirs = ["macros/sql", "macros/cross_db", "macros/schema_tests", "models", "tests"]
+
+    let totalFiles = 0
+    let ignoredFiles = 0
+
+    for (const pkg of packages) {
+      for (const sub of subdirs) {
+        for (let i = 0; i < 15; i++) {
+          const filePath = `dbt_packages/${pkg}/${sub}/file_${i}.sql`
+          totalFiles++
+          if (FileIgnore.match(filePath)) {
+            ignoredFiles++
+          }
+        }
+      }
+    }
+
+    // All 450 files (6 packages * 5 subdirs * 15 files) should be ignored
+    expect(totalFiles).toBe(450)
+    expect(ignoredFiles).toBe(totalFiles)
+  })
+
+  test("watcher ignore list covers common dbt dependency structures", () => {
+    // Real-world dbt package paths that caused EMFILE
+    const realWorldPaths = [
+      "dbt_packages/dbt_utils/macros/sql/generate_series.sql",
+      "dbt_packages/dbt_utils/macros/sql/get_column_values.sql",
+      "dbt_packages/dbt_utils/macros/sql/pivot.sql",
+      "dbt_packages/dbt_utils/macros/sql/union.sql",
+      "dbt_packages/dbt_utils/macros/sql/star.sql",
+      "dbt_packages/dbt_utils/macros/sql/deduplicate.sql",
+      "dbt_packages/dbt_utils/macros/sql/safe_subtract.sql",
+      "dbt_packages/dbt_utils/macros/sql/unpivot.sql",
+      "dbt_packages/dbt_utils/macros/cross_db_utils/dateadd.sql",
+      "dbt_packages/dbt_utils/macros/cross_db_utils/datediff.sql",
+      "dbt_packages/dbt_utils/macros/cross_db_utils/hash.sql",
+      "dbt_packages/dbt_utils/macros/cross_db_utils/split_part.sql",
+      "dbt_packages/dbt_utils/macros/web/get_url_parameter.sql",
+      "dbt_packages/dbt_utils/macros/generic_tests/at_least_one.sql",
+      "dbt_packages/dbt_utils/macros/generic_tests/not_constant.sql",
+      "dbt_packages/dbt_utils/macros/generic_tests/recency.sql",
+      "dbt_packages/dbt_utils/macros/materializations/insert_by_period.sql",
+      "dbt_packages/dbt_expectations/macros/schema_tests/expect_column_values_to_be_unique.sql",
+      "dbt_packages/dbt_expectations/macros/schema_tests/expect_column_to_exist.sql",
+      "dbt_packages/dbt_expectations/macros/schema_tests/expect_table_row_count_to_equal.sql",
+      "dbt_packages/codegen/macros/generate_source.sql",
+      "dbt_packages/codegen/macros/generate_model_yaml.sql",
+      "dbt_packages/codegen/macros/generate_base_model.sql",
+    ]
+
+    for (const p of realWorldPaths) {
+      expect(FileIgnore.match(p)).toBe(true)
+    }
+  })
+})