feat(config): add experimental.hashline_edit flag and provider state module

src/config/schema.test.ts

@@ -663,6 +663,59 @@ describe("ExperimentalConfigSchema feature flags", () => {
       expect(result.data.safe_hook_creation).toBeUndefined()
     }
   })
+
+  test("accepts hashline_edit as true", () => {
+    //#given
+    const config = { hashline_edit: true }
+
+    //#when
+    const result = ExperimentalConfigSchema.safeParse(config)
+
+    //#then
+    expect(result.success).toBe(true)
+    if (result.success) {
+      expect(result.data.hashline_edit).toBe(true)
+    }
+  })
+
+  test("accepts hashline_edit as false", () => {
+    //#given
+    const config = { hashline_edit: false }
+
+    //#when
+    const result = ExperimentalConfigSchema.safeParse(config)
+
+    //#then
+    expect(result.success).toBe(true)
+    if (result.success) {
+      expect(result.data.hashline_edit).toBe(false)
+    }
+  })
+
+  test("hashline_edit is optional", () => {
+    //#given
+    const config = { safe_hook_creation: true }
+
+    //#when
+    const result = ExperimentalConfigSchema.safeParse(config)
+
+    //#then
+    expect(result.success).toBe(true)
+    if (result.success) {
+      expect(result.data.hashline_edit).toBeUndefined()
+    }
+  })
+
+  test("rejects non-boolean hashline_edit", () => {
+    //#given
+    const config = { hashline_edit: "true" }
+
+    //#when
+    const result = ExperimentalConfigSchema.safeParse(config)
+
+    //#then
+    expect(result.success).toBe(false)
+  })
 })
 
 describe("GitMasterConfigSchema", () => {

src/config/schema/experimental.ts

@@ -15,6 +15,8 @@ export const ExperimentalConfigSchema = z.object({
   plugin_load_timeout_ms: z.number().min(1000).optional(),
   /** Wrap hook creation in try/catch to prevent one failing hook from crashing the plugin (default: true at call site) */
   safe_hook_creation: z.boolean().optional(),
+  /** Enable hashline_edit tool for improved file editing with hash-based line anchors */
+  hashline_edit: z.boolean().optional(),
 })
 
 export type ExperimentalConfig = z.infer<typeof ExperimentalConfigSchema>