diff --git a/backend/.sqlx/query-934682901882acc939b82cb04fba66dedf5f3d4775601cdb0be9988b35438c09.json b/backend/.sqlx/query-0cb9073512165a38ad21dc1fdb88548b8e8e0a369eb18228287a19ada5ee402c.json
similarity index 76%
rename from backend/.sqlx/query-934682901882acc939b82cb04fba66dedf5f3d4775601cdb0be9988b35438c09.json
rename to backend/.sqlx/query-0cb9073512165a38ad21dc1fdb88548b8e8e0a369eb18228287a19ada5ee402c.json
index 00c550be..ef8fc9e2 100644
--- a/backend/.sqlx/query-934682901882acc939b82cb04fba66dedf5f3d4775601cdb0be9988b35438c09.json
+++ b/backend/.sqlx/query-0cb9073512165a38ad21dc1fdb88548b8e8e0a369eb18228287a19ada5ee402c.json
@@ -1,6 +1,6 @@
 {
   "db_name": "SQLite",
-  "query": "SELECT id as \"id!: Uuid\", task_id as \"task_id!: Uuid\", worktree_path, branch, merge_commit, executor, pr_url, pr_number, pr_status, pr_merged_at as \"pr_merged_at: DateTime<Utc>\", created_at as \"created_at!: DateTime<Utc>\", updated_at as \"updated_at!: DateTime<Utc>\"\n               FROM task_attempts \n               WHERE task_id = $1 \n               ORDER BY created_at DESC",
+  "query": "SELECT id as \"id!: Uuid\", task_id as \"task_id!: Uuid\", worktree_path, branch, base_branch, merge_commit, executor, pr_url, pr_number, pr_status, pr_merged_at as \"pr_merged_at: DateTime<Utc>\", created_at as \"created_at!: DateTime<Utc>\", updated_at as \"updated_at!: DateTime<Utc>\"\n               FROM task_attempts \n               WHERE id = $1",
   "describe": {
     "columns": [
       {
@@ -24,43 +24,48 @@
         "type_info": "Text"
       },
       {
-        "name": "merge_commit",
+        "name": "base_branch",
         "ordinal": 4,
         "type_info": "Text"
       },
       {
-        "name": "executor",
+        "name": "merge_commit",
         "ordinal": 5,
         "type_info": "Text"
       },
       {
-        "name": "pr_url",
+        "name": "executor",
         "ordinal": 6,
         "type_info": "Text"
       },
       {
-        "name": "pr_number",
+        "name": "pr_url",
         "ordinal": 7,
+        "type_info": "Text"
+      },
+      {
+        "name": "pr_number",
+        "ordinal": 8,
         "type_info": "Integer"
       },
       {
         "name": "pr_status",
-        "ordinal": 8,
+        "ordinal": 9,
         "type_info": "Text"
       },
       {
         "name": "pr_merged_at: DateTime<Utc>",
-        "ordinal": 9,
+        "ordinal": 10,
         "type_info": "Datetime"
       },
       {
         "name": "created_at!: DateTime<Utc>",
-        "ordinal": 10,
+        "ordinal": 11,
         "type_info": "Text"
       },
       {
         "name": "updated_at!: DateTime<Utc>",
-        "ordinal": 11,
+        "ordinal": 12,
         "type_info": "Text"
       }
     ],
@@ -72,6 +77,7 @@
       false,
       false,
       false,
+      false,
       true,
       true,
       true,
@@ -82,5 +88,5 @@
       false
     ]
   },
-  "hash": "934682901882acc939b82cb04fba66dedf5f3d4775601cdb0be9988b35438c09"
+  "hash": "0cb9073512165a38ad21dc1fdb88548b8e8e0a369eb18228287a19ada5ee402c"
 }
diff --git a/backend/.sqlx/query-36f9435579ce655f583eeeb419353541c30a8b4c1e047ea89d204645293bd44e.json b/backend/.sqlx/query-5634c7b542833bc811d47391bfab0af14914e93b0dc1e9ec9de8869fe661a2d4.json
similarity index 69%
rename from backend/.sqlx/query-36f9435579ce655f583eeeb419353541c30a8b4c1e047ea89d204645293bd44e.json
rename to backend/.sqlx/query-5634c7b542833bc811d47391bfab0af14914e93b0dc1e9ec9de8869fe661a2d4.json
index d02f2cfe..a1bb2a05 100644
--- a/backend/.sqlx/query-36f9435579ce655f583eeeb419353541c30a8b4c1e047ea89d204645293bd44e.json
+++ b/backend/.sqlx/query-5634c7b542833bc811d47391bfab0af14914e93b0dc1e9ec9de8869fe661a2d4.json
@@ -1,6 +1,6 @@
 {
   "db_name": "SQLite",
-  "query": "INSERT INTO task_attempts (id, task_id, worktree_path, branch, merge_commit, executor, pr_url, pr_number, pr_status, pr_merged_at) \n               VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10) \n               RETURNING id as \"id!: Uuid\", task_id as \"task_id!: Uuid\", worktree_path, branch, merge_commit, executor, pr_url, pr_number, pr_status, pr_merged_at as \"pr_merged_at: DateTime<Utc>\", created_at as \"created_at!: DateTime<Utc>\", updated_at as \"updated_at!: DateTime<Utc>\"",
+  "query": "INSERT INTO task_attempts (id, task_id, worktree_path, branch, base_branch, merge_commit, executor, pr_url, pr_number, pr_status, pr_merged_at) \n               VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11) \n               RETURNING id as \"id!: Uuid\", task_id as \"task_id!: Uuid\", worktree_path, branch, base_branch, merge_commit, executor, pr_url, pr_number, pr_status, pr_merged_at as \"pr_merged_at: DateTime<Utc>\", created_at as \"created_at!: DateTime<Utc>\", updated_at as \"updated_at!: DateTime<Utc>\"",
   "describe": {
     "columns": [
       {
@@ -24,54 +24,60 @@
         "type_info": "Text"
       },
       {
-        "name": "merge_commit",
+        "name": "base_branch",
         "ordinal": 4,
         "type_info": "Text"
       },
       {
-        "name": "executor",
+        "name": "merge_commit",
         "ordinal": 5,
         "type_info": "Text"
       },
       {
-        "name": "pr_url",
+        "name": "executor",
         "ordinal": 6,
         "type_info": "Text"
       },
       {
-        "name": "pr_number",
+        "name": "pr_url",
         "ordinal": 7,
+        "type_info": "Text"
+      },
+      {
+        "name": "pr_number",
+        "ordinal": 8,
         "type_info": "Integer"
       },
       {
         "name": "pr_status",
-        "ordinal": 8,
+        "ordinal": 9,
         "type_info": "Text"
       },
       {
         "name": "pr_merged_at: DateTime<Utc>",
-        "ordinal": 9,
+        "ordinal": 10,
         "type_info": "Datetime"
       },
       {
         "name": "created_at!: DateTime<Utc>",
-        "ordinal": 10,
+        "ordinal": 11,
         "type_info": "Text"
       },
       {
         "name": "updated_at!: DateTime<Utc>",
-        "ordinal": 11,
+        "ordinal": 12,
         "type_info": "Text"
       }
     ],
     "parameters": {
-      "Right": 10
+      "Right": 11
     },
     "nullable": [
       true,
       false,
       false,
       false,
+      false,
       true,
       true,
       true,
@@ -82,5 +88,5 @@
       false
     ]
   },
-  "hash": "36f9435579ce655f583eeeb419353541c30a8b4c1e047ea89d204645293bd44e"
+  "hash": "5634c7b542833bc811d47391bfab0af14914e93b0dc1e9ec9de8869fe661a2d4"
 }
diff --git a/backend/.sqlx/query-c0e3402045a18d43bcbb882c9ea158f01d116d92f7f7e0fd467af8e2066dc638.json b/backend/.sqlx/query-6d3d6f10f57247d29724962eb428fee95dbdc4ae87f8c90b7bbd7f5c88d5a271.json
similarity index 71%
rename from backend/.sqlx/query-c0e3402045a18d43bcbb882c9ea158f01d116d92f7f7e0fd467af8e2066dc638.json
rename to backend/.sqlx/query-6d3d6f10f57247d29724962eb428fee95dbdc4ae87f8c90b7bbd7f5c88d5a271.json
index 54e3f7e6..a1de8c07 100644
--- a/backend/.sqlx/query-c0e3402045a18d43bcbb882c9ea158f01d116d92f7f7e0fd467af8e2066dc638.json
+++ b/backend/.sqlx/query-6d3d6f10f57247d29724962eb428fee95dbdc4ae87f8c90b7bbd7f5c88d5a271.json
@@ -1,6 +1,6 @@
 {
   "db_name": "SQLite",
-  "query": "SELECT ta.id as \"id!: Uuid\", ta.task_id as \"task_id!: Uuid\", ta.worktree_path, ta.branch, ta.merge_commit, ta.executor, ta.pr_url, ta.pr_number, ta.pr_status, ta.pr_merged_at as \"pr_merged_at: DateTime<Utc>\", ta.created_at as \"created_at!: DateTime<Utc>\", ta.updated_at as \"updated_at!: DateTime<Utc>\"\n               FROM task_attempts ta \n               JOIN tasks t ON ta.task_id = t.id \n               WHERE ta.id = $1 AND t.id = $2 AND t.project_id = $3",
+  "query": "SELECT ta.id as \"id!: Uuid\", ta.task_id as \"task_id!: Uuid\", ta.worktree_path, ta.branch, ta.base_branch, ta.merge_commit, ta.executor, ta.pr_url, ta.pr_number, ta.pr_status, ta.pr_merged_at as \"pr_merged_at: DateTime<Utc>\", ta.created_at as \"created_at!: DateTime<Utc>\", ta.updated_at as \"updated_at!: DateTime<Utc>\"\n               FROM task_attempts ta \n               JOIN tasks t ON ta.task_id = t.id \n               WHERE ta.id = $1 AND t.id = $2 AND t.project_id = $3",
   "describe": {
     "columns": [
       {
@@ -24,43 +24,48 @@
         "type_info": "Text"
       },
       {
-        "name": "merge_commit",
+        "name": "base_branch",
         "ordinal": 4,
         "type_info": "Text"
       },
       {
-        "name": "executor",
+        "name": "merge_commit",
         "ordinal": 5,
         "type_info": "Text"
       },
       {
-        "name": "pr_url",
+        "name": "executor",
         "ordinal": 6,
         "type_info": "Text"
       },
       {
-        "name": "pr_number",
+        "name": "pr_url",
         "ordinal": 7,
+        "type_info": "Text"
+      },
+      {
+        "name": "pr_number",
+        "ordinal": 8,
         "type_info": "Integer"
       },
       {
         "name": "pr_status",
-        "ordinal": 8,
+        "ordinal": 9,
         "type_info": "Text"
       },
       {
         "name": "pr_merged_at: DateTime<Utc>",
-        "ordinal": 9,
+        "ordinal": 10,
         "type_info": "Datetime"
       },
       {
         "name": "created_at!: DateTime<Utc>",
-        "ordinal": 10,
+        "ordinal": 11,
         "type_info": "Text"
       },
       {
         "name": "updated_at!: DateTime<Utc>",
-        "ordinal": 11,
+        "ordinal": 12,
         "type_info": "Text"
       }
     ],
@@ -72,6 +77,7 @@
       false,
       false,
       false,
+      false,
       true,
       true,
       true,
@@ -82,5 +88,5 @@
       false
     ]
   },
-  "hash": "c0e3402045a18d43bcbb882c9ea158f01d116d92f7f7e0fd467af8e2066dc638"
+  "hash": "6d3d6f10f57247d29724962eb428fee95dbdc4ae87f8c90b7bbd7f5c88d5a271"
 }
diff --git a/backend/.sqlx/query-7193dead2b112b137880482fe8e8c822c67ef6692e0456683331a438a4aa002f.json b/backend/.sqlx/query-7193dead2b112b137880482fe8e8c822c67ef6692e0456683331a438a4aa002f.json
deleted file mode 100644
index 02229377..00000000
--- a/backend/.sqlx/query-7193dead2b112b137880482fe8e8c822c67ef6692e0456683331a438a4aa002f.json
+++ /dev/null
@@ -1,56 +0,0 @@
-{
-  "db_name": "SQLite",
-  "query": "SELECT id as \"id!: Uuid\", project_id as \"project_id!: Uuid\", title, description, status as \"status!: TaskStatus\", created_at as \"created_at!: DateTime<Utc>\", updated_at as \"updated_at!: DateTime<Utc>\"\n               FROM tasks \n               WHERE project_id = $1 AND title = $2\n               LIMIT 1",
-  "describe": {
-    "columns": [
-      {
-        "name": "id!: Uuid",
-        "ordinal": 0,
-        "type_info": "Blob"
-      },
-      {
-        "name": "project_id!: Uuid",
-        "ordinal": 1,
-        "type_info": "Blob"
-      },
-      {
-        "name": "title",
-        "ordinal": 2,
-        "type_info": "Text"
-      },
-      {
-        "name": "description",
-        "ordinal": 3,
-        "type_info": "Text"
-      },
-      {
-        "name": "status!: TaskStatus",
-        "ordinal": 4,
-        "type_info": "Text"
-      },
-      {
-        "name": "created_at!: DateTime<Utc>",
-        "ordinal": 5,
-        "type_info": "Text"
-      },
-      {
-        "name": "updated_at!: DateTime<Utc>",
-        "ordinal": 6,
-        "type_info": "Text"
-      }
-    ],
-    "parameters": {
-      "Right": 2
-    },
-    "nullable": [
-      true,
-      false,
-      false,
-      true,
-      false,
-      false,
-      false
-    ]
-  },
-  "hash": "7193dead2b112b137880482fe8e8c822c67ef6692e0456683331a438a4aa002f"
-}
diff --git a/backend/.sqlx/query-b0e812c0c8e6456e1ae11a89e8c03e29727de9d08652b61350e0555d348ecc59.json b/backend/.sqlx/query-849ce16b3d341fe420816fe91c345a44475a4383221bfe7711e1ee1b5b3b0aeb.json
similarity index 74%
rename from backend/.sqlx/query-b0e812c0c8e6456e1ae11a89e8c03e29727de9d08652b61350e0555d348ecc59.json
rename to backend/.sqlx/query-849ce16b3d341fe420816fe91c345a44475a4383221bfe7711e1ee1b5b3b0aeb.json
index 58d7d732..b4b1ba6c 100644
--- a/backend/.sqlx/query-b0e812c0c8e6456e1ae11a89e8c03e29727de9d08652b61350e0555d348ecc59.json
+++ b/backend/.sqlx/query-849ce16b3d341fe420816fe91c345a44475a4383221bfe7711e1ee1b5b3b0aeb.json
@@ -1,6 +1,6 @@
 {
   "db_name": "SQLite",
-  "query": "SELECT id as \"id!: Uuid\", task_id as \"task_id!: Uuid\", worktree_path, branch, merge_commit, executor, pr_url, pr_number, pr_status, pr_merged_at as \"pr_merged_at: DateTime<Utc>\", created_at as \"created_at!: DateTime<Utc>\", updated_at as \"updated_at!: DateTime<Utc>\"\n               FROM task_attempts \n               WHERE id = $1",
+  "query": "SELECT id as \"id!: Uuid\", task_id as \"task_id!: Uuid\", worktree_path, branch, base_branch, merge_commit, executor, pr_url, pr_number, pr_status, pr_merged_at as \"pr_merged_at: DateTime<Utc>\", created_at as \"created_at!: DateTime<Utc>\", updated_at as \"updated_at!: DateTime<Utc>\"\n               FROM task_attempts \n               WHERE task_id = $1 \n               ORDER BY created_at DESC",
   "describe": {
     "columns": [
       {
@@ -24,43 +24,48 @@
         "type_info": "Text"
       },
       {
-        "name": "merge_commit",
+        "name": "base_branch",
         "ordinal": 4,
         "type_info": "Text"
       },
       {
-        "name": "executor",
+        "name": "merge_commit",
         "ordinal": 5,
         "type_info": "Text"
       },
       {
-        "name": "pr_url",
+        "name": "executor",
         "ordinal": 6,
         "type_info": "Text"
       },
       {
-        "name": "pr_number",
+        "name": "pr_url",
         "ordinal": 7,
+        "type_info": "Text"
+      },
+      {
+        "name": "pr_number",
+        "ordinal": 8,
         "type_info": "Integer"
       },
       {
         "name": "pr_status",
-        "ordinal": 8,
+        "ordinal": 9,
         "type_info": "Text"
       },
       {
         "name": "pr_merged_at: DateTime<Utc>",
-        "ordinal": 9,
+        "ordinal": 10,
         "type_info": "Datetime"
       },
       {
         "name": "created_at!: DateTime<Utc>",
-        "ordinal": 10,
+        "ordinal": 11,
         "type_info": "Text"
       },
       {
         "name": "updated_at!: DateTime<Utc>",
-        "ordinal": 11,
+        "ordinal": 12,
         "type_info": "Text"
       }
     ],
@@ -72,6 +77,7 @@
       false,
       false,
       false,
+      false,
       true,
       true,
       true,
@@ -82,5 +88,5 @@
       false
     ]
   },
-  "hash": "b0e812c0c8e6456e1ae11a89e8c03e29727de9d08652b61350e0555d348ecc59"
+  "hash": "849ce16b3d341fe420816fe91c345a44475a4383221bfe7711e1ee1b5b3b0aeb"
 }
diff --git a/backend/.sqlx/query-fe7c982685e4d98b871b03535de042e64b3b28f2c2837d064031159ea5048029.json b/backend/.sqlx/query-bb7926e3e1698b72ade97fa5f32314f0a2cf3e7eb3f472c32de2962a2cc806d4.json
similarity index 66%
rename from backend/.sqlx/query-fe7c982685e4d98b871b03535de042e64b3b28f2c2837d064031159ea5048029.json
rename to backend/.sqlx/query-bb7926e3e1698b72ade97fa5f32314f0a2cf3e7eb3f472c32de2962a2cc806d4.json
index 55cd399d..547fb4ba 100644
--- a/backend/.sqlx/query-fe7c982685e4d98b871b03535de042e64b3b28f2c2837d064031159ea5048029.json
+++ b/backend/.sqlx/query-bb7926e3e1698b72ade97fa5f32314f0a2cf3e7eb3f472c32de2962a2cc806d4.json
@@ -1,6 +1,6 @@
 {
   "db_name": "SQLite",
-  "query": "\n            SELECT  ta.id                AS \"id!: Uuid\",\n                    ta.task_id           AS \"task_id!: Uuid\",\n                    ta.worktree_path,\n                    ta.branch,\n                    ta.merge_commit,\n                    ta.executor,\n                    ta.pr_url,\n                    ta.pr_number,\n                    ta.pr_status,\n                    ta.pr_merged_at      AS \"pr_merged_at: DateTime<Utc>\",\n                    ta.created_at        AS \"created_at!: DateTime<Utc>\",\n                    ta.updated_at        AS \"updated_at!: DateTime<Utc>\"\n            FROM    task_attempts ta\n            JOIN    tasks t ON ta.task_id = t.id\n            WHERE   ta.id = $1\n              AND   t.id  = $2\n              AND   t.project_id = $3\n        ",
+  "query": "\n            SELECT  ta.id                AS \"id!: Uuid\",\n                    ta.task_id           AS \"task_id!: Uuid\",\n                    ta.worktree_path,\n                    ta.branch,\n                    ta.base_branch,\n                    ta.merge_commit,\n                    ta.executor,\n                    ta.pr_url,\n                    ta.pr_number,\n                    ta.pr_status,\n                    ta.pr_merged_at      AS \"pr_merged_at: DateTime<Utc>\",\n                    ta.created_at        AS \"created_at!: DateTime<Utc>\",\n                    ta.updated_at        AS \"updated_at!: DateTime<Utc>\"\n            FROM    task_attempts ta\n            JOIN    tasks t ON ta.task_id = t.id\n            WHERE   ta.id = $1\n              AND   t.id  = $2\n              AND   t.project_id = $3\n        ",
   "describe": {
     "columns": [
       {
@@ -24,43 +24,48 @@
         "type_info": "Text"
       },
       {
-        "name": "merge_commit",
+        "name": "base_branch",
         "ordinal": 4,
         "type_info": "Text"
       },
       {
-        "name": "executor",
+        "name": "merge_commit",
         "ordinal": 5,
         "type_info": "Text"
       },
       {
-        "name": "pr_url",
+        "name": "executor",
         "ordinal": 6,
         "type_info": "Text"
       },
       {
-        "name": "pr_number",
+        "name": "pr_url",
         "ordinal": 7,
+        "type_info": "Text"
+      },
+      {
+        "name": "pr_number",
+        "ordinal": 8,
         "type_info": "Integer"
       },
       {
         "name": "pr_status",
-        "ordinal": 8,
+        "ordinal": 9,
         "type_info": "Text"
       },
       {
         "name": "pr_merged_at: DateTime<Utc>",
-        "ordinal": 9,
+        "ordinal": 10,
         "type_info": "Datetime"
       },
       {
         "name": "created_at!: DateTime<Utc>",
-        "ordinal": 10,
+        "ordinal": 11,
         "type_info": "Text"
       },
       {
         "name": "updated_at!: DateTime<Utc>",
-        "ordinal": 11,
+        "ordinal": 12,
         "type_info": "Text"
       }
     ],
@@ -72,6 +77,7 @@
       false,
       false,
       false,
+      false,
       true,
       true,
       true,
@@ -82,5 +88,5 @@
       false
     ]
   },
-  "hash": "fe7c982685e4d98b871b03535de042e64b3b28f2c2837d064031159ea5048029"
+  "hash": "bb7926e3e1698b72ade97fa5f32314f0a2cf3e7eb3f472c32de2962a2cc806d4"
 }
diff --git a/backend/migrations/20250708000000_add_base_branch_to_task_attempts.sql b/backend/migrations/20250708000000_add_base_branch_to_task_attempts.sql
new file mode 100644
index 00000000..c9e057bf
--- /dev/null
+++ b/backend/migrations/20250708000000_add_base_branch_to_task_attempts.sql
@@ -0,0 +1,2 @@
+-- Add base_branch column to task_attempts table with default value
+ALTER TABLE task_attempts ADD COLUMN base_branch TEXT NOT NULL DEFAULT 'main';
diff --git a/backend/src/models/task_attempt.rs b/backend/src/models/task_attempt.rs
index 7a777590..5ecf72a0 100644
--- a/backend/src/models/task_attempt.rs
+++ b/backend/src/models/task_attempt.rs
@@ -67,7 +67,8 @@ pub struct TaskAttempt {
     pub id: Uuid,
     pub task_id: Uuid, // Foreign key to Task
     pub worktree_path: String,
-    pub branch: String, // Git branch name for this task attempt
+    pub branch: String,      // Git branch name for this task attempt
+    pub base_branch: String, // Base branch this attempt is based on
     pub merge_commit: Option<String>,
     pub executor: Option<String>,  // Name of the executor to use
     pub pr_url: Option<String>,    // GitHub PR URL
@@ -175,7 +176,7 @@ impl TaskAttempt {
     pub async fn find_by_id(pool: &SqlitePool, id: Uuid) -> Result<Option<Self>, sqlx::Error> {
         sqlx::query_as!(
             TaskAttempt,
-            r#"SELECT id as "id!: Uuid", task_id as "task_id!: Uuid", worktree_path, branch, merge_commit, executor, pr_url, pr_number, pr_status, pr_merged_at as "pr_merged_at: DateTime<Utc>", created_at as "created_at!: DateTime<Utc>", updated_at as "updated_at!: DateTime<Utc>"
+            r#"SELECT id as "id!: Uuid", task_id as "task_id!: Uuid", worktree_path, branch, base_branch, merge_commit, executor, pr_url, pr_number, pr_status, pr_merged_at as "pr_merged_at: DateTime<Utc>", created_at as "created_at!: DateTime<Utc>", updated_at as "updated_at!: DateTime<Utc>"
                FROM task_attempts 
                WHERE id = $1"#,
             id
@@ -190,7 +191,7 @@ impl TaskAttempt {
     ) -> Result<Vec<Self>, sqlx::Error> {
         sqlx::query_as!(
             TaskAttempt,
-            r#"SELECT id as "id!: Uuid", task_id as "task_id!: Uuid", worktree_path, branch, merge_commit, executor, pr_url, pr_number, pr_status, pr_merged_at as "pr_merged_at: DateTime<Utc>", created_at as "created_at!: DateTime<Utc>", updated_at as "updated_at!: DateTime<Utc>"
+            r#"SELECT id as "id!: Uuid", task_id as "task_id!: Uuid", worktree_path, branch, base_branch, merge_commit, executor, pr_url, pr_number, pr_status, pr_merged_at as "pr_merged_at: DateTime<Utc>", created_at as "created_at!: DateTime<Utc>", updated_at as "updated_at!: DateTime<Utc>"
                FROM task_attempts 
                WHERE task_id = $1 
                ORDER BY created_at DESC"#,
@@ -231,6 +232,25 @@ impl TaskAttempt {
             .await?
             .ok_or(TaskAttemptError::ProjectNotFound)?;
 
+        // Determine the resolved base branch name first
+        let resolved_base_branch = if let Some(ref base_branch) = data.base_branch {
+            base_branch.clone()
+        } else {
+            // Default to current HEAD branch name or "main"
+            let repo = Repository::open(&project.git_repo_path)?;
+            let default_branch = match repo.head() {
+                Ok(head_ref) => head_ref.shorthand().unwrap_or("main").to_string(),
+                Err(e)
+                    if e.class() == git2::ErrorClass::Reference
+                        && e.code() == git2::ErrorCode::UnbornBranch =>
+                {
+                    "main".to_string() // Repository has no commits yet
+                }
+                Err(_) => "main".to_string(), // Fallback
+            };
+            default_branch
+        };
+
         // Solve scoping issues
         {
             // Create the worktree using git2
@@ -305,13 +325,14 @@ impl TaskAttempt {
         // Insert the record into the database
         Ok(sqlx::query_as!(
             TaskAttempt,
-            r#"INSERT INTO task_attempts (id, task_id, worktree_path, branch, merge_commit, executor, pr_url, pr_number, pr_status, pr_merged_at) 
-               VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10) 
-               RETURNING id as "id!: Uuid", task_id as "task_id!: Uuid", worktree_path, branch, merge_commit, executor, pr_url, pr_number, pr_status, pr_merged_at as "pr_merged_at: DateTime<Utc>", created_at as "created_at!: DateTime<Utc>", updated_at as "updated_at!: DateTime<Utc>""#,
+            r#"INSERT INTO task_attempts (id, task_id, worktree_path, branch, base_branch, merge_commit, executor, pr_url, pr_number, pr_status, pr_merged_at) 
+               VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11) 
+               RETURNING id as "id!: Uuid", task_id as "task_id!: Uuid", worktree_path, branch, base_branch, merge_commit, executor, pr_url, pr_number, pr_status, pr_merged_at as "pr_merged_at: DateTime<Utc>", created_at as "created_at!: DateTime<Utc>", updated_at as "updated_at!: DateTime<Utc>""#,
             attempt_id,
             task_id,
             worktree_path_str,
             task_attempt_branch,
+            resolved_base_branch,
             Option::<String>::None, // merge_commit is always None during creation
             data.executor,
             Option::<String>::None, // pr_url is None during creation
@@ -477,7 +498,7 @@ impl TaskAttempt {
         // Get the task attempt with validation
         let attempt = sqlx::query_as!(
             TaskAttempt,
-            r#"SELECT ta.id as "id!: Uuid", ta.task_id as "task_id!: Uuid", ta.worktree_path, ta.branch, ta.merge_commit, ta.executor, ta.pr_url, ta.pr_number, ta.pr_status, ta.pr_merged_at as "pr_merged_at: DateTime<Utc>", ta.created_at as "created_at!: DateTime<Utc>", ta.updated_at as "updated_at!: DateTime<Utc>"
+            r#"SELECT ta.id as "id!: Uuid", ta.task_id as "task_id!: Uuid", ta.worktree_path, ta.branch, ta.base_branch, ta.merge_commit, ta.executor, ta.pr_url, ta.pr_number, ta.pr_status, ta.pr_merged_at as "pr_merged_at: DateTime<Utc>", ta.created_at as "created_at!: DateTime<Utc>", ta.updated_at as "updated_at!: DateTime<Utc>"
                FROM task_attempts ta 
                JOIN tasks t ON ta.task_id = t.id 
                WHERE ta.id = $1 AND t.id = $2 AND t.project_id = $3"#,
@@ -1122,7 +1143,7 @@ impl TaskAttempt {
         // Get the task attempt with validation
         let attempt = sqlx::query_as!(
             TaskAttempt,
-            r#"SELECT ta.id as "id!: Uuid", ta.task_id as "task_id!: Uuid", ta.worktree_path, ta.branch, ta.merge_commit, ta.executor, ta.pr_url, ta.pr_number, ta.pr_status, ta.pr_merged_at as "pr_merged_at: DateTime<Utc>", ta.created_at as "created_at!: DateTime<Utc>", ta.updated_at as "updated_at!: DateTime<Utc>"
+            r#"SELECT ta.id as "id!: Uuid", ta.task_id as "task_id!: Uuid", ta.worktree_path, ta.branch, ta.base_branch, ta.merge_commit, ta.executor, ta.pr_url, ta.pr_number, ta.pr_status, ta.pr_merged_at as "pr_merged_at: DateTime<Utc>", ta.created_at as "created_at!: DateTime<Utc>", ta.updated_at as "updated_at!: DateTime<Utc>"
                FROM task_attempts ta 
                JOIN tasks t ON ta.task_id = t.id 
                WHERE ta.id = $1 AND t.id = $2 AND t.project_id = $3"#,
@@ -1568,6 +1589,7 @@ impl TaskAttempt {
                     ta.task_id           AS "task_id!: Uuid",
                     ta.worktree_path,
                     ta.branch,
+                    ta.base_branch,
                     ta.merge_commit,
                     ta.executor,
                     ta.pr_url,
@@ -1608,47 +1630,33 @@ impl TaskAttempt {
         let attempt_oid = attempt_ref.target().unwrap();
 
         // ── determine the base branch & ahead/behind counts ─────────────────────────
-        let mut base_branch_name = String::from("main"); // sensible default
-        let mut commits_ahead: usize = 0;
-        let mut commits_behind: usize = 0;
-        let mut best_distance: usize = usize::MAX;
+        let base_branch_name = attempt.base_branch.clone();
 
         // 1. prefer the branch’s configured upstream, if any
         if let Ok(local_branch) = main_repo.find_branch(&attempt_branch, BranchType::Local) {
             if let Ok(upstream) = local_branch.upstream() {
-                if let Some(name) = upstream.name()? {
+                if let Some(_name) = upstream.name()? {
                     if let Some(base_oid) = upstream.get().target() {
-                        let (ahead, behind) =
+                        let (_ahead, _behind) =
                             main_repo.graph_ahead_behind(attempt_oid, base_oid)?;
-                        base_branch_name = name.to_owned();
-                        commits_ahead = ahead;
-                        commits_behind = behind;
-                        best_distance = ahead + behind;
+                        // Ignore upstream since we use stored base branch
                     }
                 }
             }
         }
 
-        // 2. otherwise, take the branch with the smallest ahead+behind distance
-        if best_distance == usize::MAX {
-            for br in main_repo.branches(None)? {
-                let (br, _) = br?;
-                let name = br.name()?.unwrap_or_default();
-                if name == attempt_branch {
-                    continue; // skip comparing the branch to itself
+        // Calculate ahead/behind counts using the stored base branch
+        let (commits_ahead, commits_behind) =
+            if let Ok(base_branch) = main_repo.find_branch(&base_branch_name, BranchType::Local) {
+                if let Some(base_oid) = base_branch.get().target() {
+                    main_repo.graph_ahead_behind(attempt_oid, base_oid)?
+                } else {
+                    (0, 0) // Base branch has no commits
                 }
-                if let Some(base_oid) = br.get().target() {
-                    let (ahead, behind) = main_repo.graph_ahead_behind(attempt_oid, base_oid)?;
-                    let distance = ahead + behind;
-                    if distance < best_distance {
-                        best_distance = distance;
-                        base_branch_name = name.to_owned();
-                        commits_ahead = ahead;
-                        commits_behind = behind;
-                    }
-                }
-            }
-        }
+            } else {
+                // Base branch doesn't exist, assume no relationship
+                (0, 0)
+            };
 
         // ── detect any uncommitted / untracked changes ───────────────────────────────
         let repo_for_status = Repository::open(&project.git_repo_path)?;
@@ -1687,7 +1695,7 @@ impl TaskAttempt {
         // Get the task attempt with validation
         let attempt = sqlx::query_as!(
             TaskAttempt,
-            r#"SELECT ta.id as "id!: Uuid", ta.task_id as "task_id!: Uuid", ta.worktree_path, ta.branch, ta.merge_commit, ta.executor, ta.pr_url, ta.pr_number, ta.pr_status, ta.pr_merged_at as "pr_merged_at: DateTime<Utc>", ta.created_at as "created_at!: DateTime<Utc>", ta.updated_at as "updated_at!: DateTime<Utc>"
+            r#"SELECT ta.id as "id!: Uuid", ta.task_id as "task_id!: Uuid", ta.worktree_path, ta.branch, ta.base_branch, ta.merge_commit, ta.executor, ta.pr_url, ta.pr_number, ta.pr_status, ta.pr_merged_at as "pr_merged_at: DateTime<Utc>", ta.created_at as "created_at!: DateTime<Utc>", ta.updated_at as "updated_at!: DateTime<Utc>"
                FROM task_attempts ta 
                JOIN tasks t ON ta.task_id = t.id 
                WHERE ta.id = $1 AND t.id = $2 AND t.project_id = $3"#,
@@ -1704,11 +1712,14 @@ impl TaskAttempt {
             .await?
             .ok_or(TaskAttemptError::ProjectNotFound)?;
 
+        // Use the stored base branch if no new base branch is provided
+        let effective_base_branch = new_base_branch.or_else(|| Some(attempt.base_branch.clone()));
+
         // Perform the git rebase operations (synchronous)
         let new_base_commit = Self::perform_rebase_operation(
             &attempt.worktree_path,
             &project.git_repo_path,
-            new_base_branch,
+            effective_base_branch,
         )?;
 
         // No need to update database as we now get base_commit live from git
@@ -1726,7 +1737,7 @@ impl TaskAttempt {
         // Get the task attempt with validation
         let attempt = sqlx::query_as!(
             TaskAttempt,
-            r#"SELECT ta.id as "id!: Uuid", ta.task_id as "task_id!: Uuid", ta.worktree_path, ta.branch, ta.merge_commit, ta.executor, ta.pr_url, ta.pr_number, ta.pr_status, ta.pr_merged_at as "pr_merged_at: DateTime<Utc>", ta.created_at as "created_at!: DateTime<Utc>", ta.updated_at as "updated_at!: DateTime<Utc>"
+            r#"SELECT ta.id as "id!: Uuid", ta.task_id as "task_id!: Uuid", ta.worktree_path, ta.branch, ta.base_branch, ta.merge_commit, ta.executor, ta.pr_url, ta.pr_number, ta.pr_status, ta.pr_merged_at as "pr_merged_at: DateTime<Utc>", ta.created_at as "created_at!: DateTime<Utc>", ta.updated_at as "updated_at!: DateTime<Utc>"
                FROM task_attempts ta 
                JOIN tasks t ON ta.task_id = t.id 
                WHERE ta.id = $1 AND t.id = $2 AND t.project_id = $3"#,
@@ -1796,7 +1807,7 @@ impl TaskAttempt {
         // Get the task attempt with validation
         let attempt = sqlx::query_as!(
             TaskAttempt,
-            r#"SELECT ta.id as "id!: Uuid", ta.task_id as "task_id!: Uuid", ta.worktree_path, ta.branch, ta.merge_commit, ta.executor, ta.pr_url, ta.pr_number, ta.pr_status, ta.pr_merged_at as "pr_merged_at: DateTime<Utc>", ta.created_at as "created_at!: DateTime<Utc>", ta.updated_at as "updated_at!: DateTime<Utc>"
+            r#"SELECT ta.id as "id!: Uuid", ta.task_id as "task_id!: Uuid", ta.worktree_path, ta.branch, ta.base_branch, ta.merge_commit, ta.executor, ta.pr_url, ta.pr_number, ta.pr_status, ta.pr_merged_at as "pr_merged_at: DateTime<Utc>", ta.created_at as "created_at!: DateTime<Utc>", ta.updated_at as "updated_at!: DateTime<Utc>"
                FROM task_attempts ta 
                JOIN tasks t ON ta.task_id = t.id 
                WHERE ta.id = $1 AND t.id = $2 AND t.project_id = $3"#,
@@ -2041,7 +2052,7 @@ impl TaskAttempt {
         // Get the task attempt with validation
         let _attempt = sqlx::query_as!(
             TaskAttempt,
-            r#"SELECT ta.id as "id!: Uuid", ta.task_id as "task_id!: Uuid", ta.worktree_path, ta.branch, ta.merge_commit, ta.executor, ta.pr_url, ta.pr_number, ta.pr_status, ta.pr_merged_at as "pr_merged_at: DateTime<Utc>", ta.created_at as "created_at!: DateTime<Utc>", ta.updated_at as "updated_at!: DateTime<Utc>"
+            r#"SELECT ta.id as "id!: Uuid", ta.task_id as "task_id!: Uuid", ta.worktree_path, ta.branch, ta.base_branch, ta.merge_commit, ta.executor, ta.pr_url, ta.pr_number, ta.pr_status, ta.pr_merged_at as "pr_merged_at: DateTime<Utc>", ta.created_at as "created_at!: DateTime<Utc>", ta.updated_at as "updated_at!: DateTime<Utc>"
                FROM task_attempts ta 
                JOIN tasks t ON ta.task_id = t.id 
                WHERE ta.id = $1 AND t.id = $2 AND t.project_id = $3"#,
diff --git a/backend/src/routes/task_attempts.rs b/backend/src/routes/task_attempts.rs
index 1d9fb230..44404236 100644
--- a/backend/src/routes/task_attempts.rs
+++ b/backend/src/routes/task_attempts.rs
@@ -329,10 +329,28 @@ pub async fn create_github_pr(
         }
     };
 
-    let base_branch = request
-        .base_branch
-        .or(config.github.default_pr_base)
-        .unwrap_or_else(|| "main".to_string());
+    // Get the task attempt to access the stored base branch
+    let attempt = match TaskAttempt::find_by_id(&app_state.db_pool, attempt_id).await {
+        Ok(Some(attempt)) => attempt,
+        Ok(None) => return Err(StatusCode::NOT_FOUND),
+        Err(e) => {
+            tracing::error!("Failed to fetch task attempt {}: {}", attempt_id, e);
+            return Err(StatusCode::INTERNAL_SERVER_ERROR);
+        }
+    };
+
+    let base_branch = request.base_branch.unwrap_or_else(|| {
+        // Use the stored base branch from the task attempt as the default
+        // Fall back to config default or "main" only if stored base branch is somehow invalid
+        if !attempt.base_branch.trim().is_empty() {
+            attempt.base_branch.clone()
+        } else {
+            config
+                .github
+                .default_pr_base
+                .unwrap_or_else(|| "main".to_string())
+        }
+    });
 
     match TaskAttempt::create_github_pr(
         &app_state.db_pool,
diff --git a/frontend/src/components/tasks/TaskDetailsToolbar.tsx b/frontend/src/components/tasks/TaskDetailsToolbar.tsx
index 6219be93..bccecb2b 100644
--- a/frontend/src/components/tasks/TaskDetailsToolbar.tsx
+++ b/frontend/src/components/tasks/TaskDetailsToolbar.tsx
@@ -17,6 +17,13 @@ import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
 import { Textarea } from '@/components/ui/textarea';
 import { Label } from '@/components/ui/label';
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from '@/components/ui/select';
 import {
   DropdownMenu,
   DropdownMenuContent,
@@ -131,7 +138,9 @@ export function TaskDetailsToolbar({
   const [showCreatePRDialog, setShowCreatePRDialog] = useState(false);
   const [prTitle, setPrTitle] = useState('');
   const [prBody, setPrBody] = useState('');
-  const [prBaseBranch, setPrBaseBranch] = useState('main');
+  const [prBaseBranch, setPrBaseBranch] = useState(
+    selectedAttempt?.base_branch || 'main'
+  );
   const [error, setError] = useState<string | null>(null);
 
   // Set create attempt mode when there are no attempts
@@ -139,6 +148,13 @@ export function TaskDetailsToolbar({
     setIsInCreateAttemptMode(taskAttempts.length === 0);
   }, [taskAttempts.length]);
 
+  // Update PR base branch when selected attempt changes
+  useEffect(() => {
+    if (selectedAttempt?.base_branch) {
+      setPrBaseBranch(selectedAttempt.base_branch);
+    }
+  }, [selectedAttempt?.base_branch]);
+
   // Branch status fetching
   const fetchBranchStatus = useCallback(async () => {
     if (!projectId || !selectedAttempt?.id || !selectedAttempt?.task_id) return;
@@ -286,7 +302,7 @@ export function TaskDetailsToolbar({
           // Reset form
           setPrTitle('');
           setPrBody('');
-          setPrBaseBranch('main');
+          setPrBaseBranch(selectedAttempt?.base_branch || 'main');
         } else {
           setError(result.message || 'Failed to create GitHub PR');
         }
@@ -908,12 +924,28 @@ export function TaskDetailsToolbar({
             </div>
             <div className="space-y-2">
               <Label htmlFor="pr-base">Base Branch</Label>
-              <Input
-                id="pr-base"
-                value={prBaseBranch}
-                onChange={(e) => setPrBaseBranch(e.target.value)}
-                placeholder="main"
-              />
+              <Select value={prBaseBranch} onValueChange={setPrBaseBranch}>
+                <SelectTrigger>
+                  <SelectValue placeholder="Select base branch" />
+                </SelectTrigger>
+                <SelectContent>
+                  {branches
+                    .filter((branch) => !branch.is_remote) // Only show local branches
+                    .map((branch) => (
+                      <SelectItem key={branch.name} value={branch.name}>
+                        {branch.name}
+                        {branch.is_current && ' (current)'}
+                      </SelectItem>
+                    ))}
+                  {/* Add common branches as fallback if not in the list */}
+                  {!branches.some((b) => b.name === 'main' && !b.is_remote) && (
+                    <SelectItem value="main">main</SelectItem>
+                  )}
+                  {!branches.some(
+                    (b) => b.name === 'master' && !b.is_remote
+                  ) && <SelectItem value="master">master</SelectItem>}
+                </SelectContent>
+              </Select>
             </div>
           </div>
           <DialogFooter>
diff --git a/shared/types.ts b/shared/types.ts
index 18522e27..35c94ddb 100644
--- a/shared/types.ts
+++ b/shared/types.ts
@@ -56,7 +56,7 @@ export type UpdateTask = { title: string | null, description: string | null, sta
 
 export type TaskAttemptStatus = "setuprunning" | "setupcomplete" | "setupfailed" | "executorrunning" | "executorcomplete" | "executorfailed";
 
-export type TaskAttempt = { id: string, task_id: string, worktree_path: string, branch: string, merge_commit: string | null, executor: string | null, pr_url: string | null, pr_number: bigint | null, pr_status: string | null, pr_merged_at: string | null, created_at: string, updated_at: string, };
+export type TaskAttempt = { id: string, task_id: string, worktree_path: string, branch: string, base_branch: string, merge_commit: string | null, executor: string | null, pr_url: string | null, pr_number: bigint | null, pr_status: string | null, pr_merged_at: string | null, created_at: string, updated_at: string, };
 
 export type CreateTaskAttempt = { executor: string | null, base_branch: string | null, };