diff --git a/.quality/dependency-compatibility.json b/.quality/dependency-compatibility.json
index 3279ced3..1a9e4df3 100644
--- a/.quality/dependency-compatibility.json
+++ b/.quality/dependency-compatibility.json
@@ -1,62 +1,18 @@
 {
-  "src/cortex-agents/Cargo.toml:dependencies:thiserror": {
-    "declaration": "1",
-    "reason": "Retains the existing thiserror 1 derive API until its consumers are migrated together."
-  },
   "src/cortex-app-server/Cargo.toml:dependencies:dirs": {
     "declaration": "5",
     "reason": "Retains dirs 5 platform path behavior until its consumers are migrated and platform-tested."
   },
-  "src/cortex-batch/Cargo.toml:dependencies:thiserror": {
-    "declaration": "1",
-    "reason": "Retains the existing thiserror 1 derive API until its consumers are migrated together."
-  },
-  "src/cortex-compact/Cargo.toml:dependencies:thiserror": {
-    "declaration": "1",
-    "reason": "Retains the existing thiserror 1 derive API until its consumers are migrated together."
-  },
   "src/cortex-engine/Cargo.toml:dependencies:rand": {
     "declaration": "0.8",
     "reason": "Retains rand 0.8 Rng/generation APIs; upgrade requires a separate compatibility change."
   },
-  "src/cortex-ghost/Cargo.toml:dependencies:thiserror": {
-    "declaration": "1",
-    "reason": "Retains the existing thiserror 1 derive API until its consumers are migrated together."
-  },
   "src/cortex-hooks/Cargo.toml:dependencies:dirs": {
     "declaration": "5.0",
     "reason": "Retains dirs 5 platform path behavior until its consumers are migrated and platform-tested."
   },
-  "src/cortex-hooks/Cargo.toml:dependencies:thiserror": {
-    "declaration": "1",
-    "reason": "Retains the existing thiserror 1 derive API until its consumers are migrated together."
-  },
-  "src/cortex-resume/Cargo.toml:dependencies:thiserror": {
-    "declaration": "1",
-    "reason": "Retains the existing thiserror 1 derive API until its consumers are migrated together."
-  },
-  "src/cortex-review/Cargo.toml:dependencies:thiserror": {
-    "declaration": "1",
-    "reason": "Retains the existing thiserror 1 derive API until its consumers are migrated together."
-  },
-  "src/cortex-share/Cargo.toml:dependencies:thiserror": {
-    "declaration": "1",
-    "reason": "Retains the existing thiserror 1 derive API until its consumers are migrated together."
-  },
-  "src/cortex-snapshot/Cargo.toml:dependencies:thiserror": {
-    "declaration": "1",
-    "reason": "Retains the existing thiserror 1 derive API until its consumers are migrated together."
-  },
   "src/cortex-storage/Cargo.toml:dependencies:dirs": {
     "declaration": "5",
     "reason": "Retains dirs 5 platform path behavior until its consumers are migrated and platform-tested."
-  },
-  "src/cortex-storage/Cargo.toml:dependencies:thiserror": {
-    "declaration": "1",
-    "reason": "Retains the existing thiserror 1 derive API until its consumers are migrated together."
-  },
-  "src/cortex-windows-sandbox/Cargo.toml:dependencies:thiserror": {
-    "declaration": "1",
-    "reason": "Retains the existing thiserror 1 derive API until its consumers are migrated together."
   }
 }
diff --git a/Cargo.lock b/Cargo.lock
index 2279dd27..13f70378 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -946,7 +946,7 @@ dependencies = [
  "serde_json",
  "serde_yaml",
  "tempfile",
- "thiserror 1.0.69",
+ "thiserror 2.0.20",
  "tokio",
  "toml 0.8.23",
  "tracing",
@@ -1013,7 +1013,7 @@ dependencies = [
  "once_cell",
  "serde",
  "tempfile",
- "thiserror 1.0.69",
+ "thiserror 2.0.20",
  "tokio",
  "tracing",
 ]
@@ -1123,7 +1123,7 @@ dependencies = [
  "libc",
  "serde",
  "tempfile",
- "thiserror 1.0.69",
+ "thiserror 2.0.20",
  "tracing",
 ]
 
@@ -1285,7 +1285,7 @@ dependencies = [
  "cortex-common",
  "serde",
  "tempfile",
- "thiserror 1.0.69",
+ "thiserror 2.0.20",
  "tokio",
  "tracing",
 ]
@@ -1301,7 +1301,7 @@ dependencies = [
  "lazy_static",
  "serde",
  "serde_json",
- "thiserror 1.0.69",
+ "thiserror 2.0.20",
  "tokio",
  "tracing",
 ]
@@ -1536,7 +1536,7 @@ dependencies = [
  "serde",
  "serde_json",
  "tempfile",
- "thiserror 1.0.69",
+ "thiserror 2.0.20",
  "tokio",
  "tracing",
 ]
@@ -1546,7 +1546,7 @@ name = "cortex-review"
 version = "0.1.0"
 dependencies = [
  "serde",
- "thiserror 1.0.69",
+ "thiserror 2.0.20",
  "tokio",
 ]
 
@@ -1572,7 +1572,7 @@ dependencies = [
  "reqwest 0.13.4",
  "serde",
  "serde_json",
- "thiserror 1.0.69",
+ "thiserror 2.0.20",
  "tokio",
  "tracing",
 ]
@@ -1639,7 +1639,7 @@ dependencies = [
  "serde_json",
  "sha2",
  "tempfile",
- "thiserror 1.0.69",
+ "thiserror 2.0.20",
  "tokio",
  "tracing",
  "uuid",
@@ -1654,7 +1654,7 @@ dependencies = [
  "serde",
  "serde_json",
  "tempfile",
- "thiserror 1.0.69",
+ "thiserror 2.0.20",
  "tokio",
  "tracing",
  "uuid",
@@ -1898,7 +1898,7 @@ name = "cortex-windows-sandbox"
 version = "0.1.0"
 dependencies = [
  "serde",
- "thiserror 1.0.69",
+ "thiserror 2.0.20",
  "tracing",
  "windows 0.58.0",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 73363f27..d26a01e0 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -131,7 +131,7 @@ toml = "0.8"
 reqwest = { version = "0.13", features = ["json", "stream", "rustls", "cookies", "form", "multipart", "query"], default-features = false }
 
 # Error handling
-thiserror = "2.0.18"
+thiserror = "2.0.20"
 anyhow = "1.0"
 
 # Tracing & Observability
diff --git a/src/cortex-agents/Cargo.toml b/src/cortex-agents/Cargo.toml
index e1251492..19a34e98 100644
--- a/src/cortex-agents/Cargo.toml
+++ b/src/cortex-agents/Cargo.toml
@@ -18,7 +18,7 @@ toml = { workspace = true }
 async-trait = { workspace = true }
 async-recursion = "1"
 tracing = { workspace = true }
-thiserror = "1"
+thiserror = { workspace = true }
 uuid = { workspace = true, features = ["v4"] }
 regex = { workspace = true }
 dirs = { workspace = true }
diff --git a/src/cortex-batch/Cargo.toml b/src/cortex-batch/Cargo.toml
index 777462ef..158bff37 100644
--- a/src/cortex-batch/Cargo.toml
+++ b/src/cortex-batch/Cargo.toml
@@ -13,7 +13,7 @@ cortex-common = { workspace = true }
 tokio = { workspace = true, features = ["fs", "time", "sync"] }
 serde = { workspace = true, features = ["derive"] }
 tracing = { workspace = true }
-thiserror = "1"
+thiserror = { workspace = true }
 glob = { workspace = true }
 once_cell = { workspace = true }
 
diff --git a/src/cortex-compact/Cargo.toml b/src/cortex-compact/Cargo.toml
index f25a0fc6..d245e247 100644
--- a/src/cortex-compact/Cargo.toml
+++ b/src/cortex-compact/Cargo.toml
@@ -12,7 +12,7 @@ workspace = true
 cortex-common = { workspace = true }
 serde = { workspace = true, features = ["derive"] }
 tracing = { workspace = true }
-thiserror = "1"
+thiserror = { workspace = true }
 
 # For disk space detection on Unix
 [target.'cfg(unix)'.dependencies]
diff --git a/src/cortex-ghost/Cargo.toml b/src/cortex-ghost/Cargo.toml
index 1d3f38be..10a9b196 100644
--- a/src/cortex-ghost/Cargo.toml
+++ b/src/cortex-ghost/Cargo.toml
@@ -13,6 +13,6 @@ cortex-common = { workspace = true }
 tokio = { workspace = true, features = ["process"] }
 serde = { workspace = true, features = ["derive"] }
 tracing = { workspace = true }
-thiserror = "1"
+thiserror = { workspace = true }
 chrono = { workspace = true, features = ["serde"] }
 tempfile = { workspace = true }
diff --git a/src/cortex-hooks/Cargo.toml b/src/cortex-hooks/Cargo.toml
index 53049e11..f5b2cf9f 100644
--- a/src/cortex-hooks/Cargo.toml
+++ b/src/cortex-hooks/Cargo.toml
@@ -14,7 +14,7 @@ tokio = { workspace = true, features = ["process", "sync"] }
 serde = { workspace = true, features = ["derive"] }
 serde_json = { workspace = true }
 tracing = { workspace = true }
-thiserror = "1"
+thiserror = { workspace = true }
 glob = { workspace = true }
 lazy_static = { workspace = true }
 dirs = "5.0"
diff --git a/src/cortex-resume/Cargo.toml b/src/cortex-resume/Cargo.toml
index 6b11a3e2..7bef4675 100644
--- a/src/cortex-resume/Cargo.toml
+++ b/src/cortex-resume/Cargo.toml
@@ -13,7 +13,7 @@ tokio = { workspace = true, features = ["fs", "time", "sync"] }
 serde = { workspace = true, features = ["derive"] }
 serde_json = { workspace = true }
 tracing = { workspace = true }
-thiserror = "1"
+thiserror = { workspace = true }
 chrono = { workspace = true, features = ["serde"] }
 once_cell = { workspace = true }
 
diff --git a/src/cortex-review/Cargo.toml b/src/cortex-review/Cargo.toml
index 73814216..9f8bc856 100644
--- a/src/cortex-review/Cargo.toml
+++ b/src/cortex-review/Cargo.toml
@@ -11,4 +11,4 @@ workspace = true
 [dependencies]
 tokio = { workspace = true, features = ["process"] }
 serde = { workspace = true, features = ["derive"] }
-thiserror = "1"
+thiserror = { workspace = true }
diff --git a/src/cortex-share/Cargo.toml b/src/cortex-share/Cargo.toml
index ea3a45f9..29c62f29 100644
--- a/src/cortex-share/Cargo.toml
+++ b/src/cortex-share/Cargo.toml
@@ -14,6 +14,6 @@ tokio = { workspace = true }
 serde = { workspace = true, features = ["derive"] }
 serde_json = { workspace = true }
 tracing = { workspace = true }
-thiserror = "1"
+thiserror = { workspace = true }
 reqwest = { workspace = true }
 chrono = { workspace = true, features = ["serde"] }
diff --git a/src/cortex-snapshot/Cargo.toml b/src/cortex-snapshot/Cargo.toml
index 23700334..7b6e86f5 100644
--- a/src/cortex-snapshot/Cargo.toml
+++ b/src/cortex-snapshot/Cargo.toml
@@ -13,7 +13,7 @@ tokio = { workspace = true, features = ["process"] }
 serde = { workspace = true, features = ["derive"] }
 serde_json = { workspace = true }
 tracing = { workspace = true }
-thiserror = "1"
+thiserror = { workspace = true }
 chrono = { workspace = true, features = ["serde"] }
 uuid = { workspace = true, features = ["v4"] }
 sha2 = { workspace = true }
diff --git a/src/cortex-storage/Cargo.toml b/src/cortex-storage/Cargo.toml
index 3e00b968..c93b283f 100644
--- a/src/cortex-storage/Cargo.toml
+++ b/src/cortex-storage/Cargo.toml
@@ -29,7 +29,7 @@ chrono = { workspace = true, features = ["serde"] }
 uuid = { workspace = true, features = ["v4", "serde"] }
 
 # Error handling
-thiserror = "1"
+thiserror = { workspace = true }
 
 [dev-dependencies]
 tempfile = { workspace = true }
diff --git a/src/cortex-windows-sandbox/Cargo.toml b/src/cortex-windows-sandbox/Cargo.toml
index f13a11f0..1925ecee 100644
--- a/src/cortex-windows-sandbox/Cargo.toml
+++ b/src/cortex-windows-sandbox/Cargo.toml
@@ -21,4 +21,4 @@ workspace = true
 [dependencies]
 serde = { workspace = true, features = ["derive"] }
 tracing = { workspace = true }
-thiserror = "1"
\ No newline at end of file
+thiserror = { workspace = true }
\ No newline at end of file