diff --git a/internal/config/allowlist/allowed_ext_test.go b/internal/config/allowlist/allowed_ext_test.go
index 83abb167c..d8e59d06e 100644
--- a/internal/config/allowlist/allowed_ext_test.go
+++ b/internal/config/allowlist/allowed_ext_test.go
@@ -79,6 +79,10 @@ func TestIsAllowedExt(t *testing.T) {
 		{".LIBSONNET", true},
 		{".zig", true},
 		{".ZIG", true},
+		{".thrift", true},
+		{".THRIFT", true},
+		{".capnp", true},
+		{".CAPNP", true},
 		{".txt", false},
 		{".md", false},
 		{".png", false},
@@ -200,6 +204,24 @@ func TestIsExcludedPath(t *testing.T) {
 		{"elm nested test directory", "packages/core/tests/unit/ParserTest.elm", true},
 		{"elm non-test", "src/Parser.elm", false},
 		{"elm tests in filename", "src/TestsHelper.elm", false},
+		// Thrift generated output directories
+		{"kitex_gen at root", "kitex_gen/api/service.go", true},
+		{"kitex_gen nested", "app/rpc/kitex_gen/user/user.go", true},
+		{"thrift idl is reviewed", "idl/service.thrift", false},
+		{"hand-written generated-ish dir name", "services/generated_client/client.go", false},
+		{"gen in package name only", "internal/generator/main.go", false},
+		// The kitex_gen pattern is extension-anchored: a colliding directory name
+		// must not drop files Thrift never emits (IsExcludedPath has no language dispatch).
+		{"kitex_gen holding non-Go file", "kitex_gen/api/schema.json", false},
+
+		// Cap'n Proto generated output files
+		{"capnp generated header", "src/schema.capnp.h", true},
+		{"capnp generated go", "tunnelrpc/proto/tunnelrpc.capnp.go", true},
+		{"capnp generated rust", "src/element_capnp.rs", true},
+		{"capnp generated typescript", "src/rpc.capnp.ts", true},
+		{"capnp generated python", "schema/addressbook_capnp.py", true},
+		{"capnp schema is reviewed", "schema/addressbook.capnp", false},
+		{"capnp in filename only", "src/capnp_helpers.go", false},
 
 		// Jsonnet vendored dependencies (written by `jb install`, wiped by `rm -rf vendor`).
 		// The pattern is extension-scoped: IsExcludedPath applies every pattern to every
diff --git a/internal/config/allowlist/default_exclude_patterns.json b/internal/config/allowlist/default_exclude_patterns.json
index 9f05b470b..b88d85086 100644
--- a/internal/config/allowlist/default_exclude_patterns.json
+++ b/internal/config/allowlist/default_exclude_patterns.json
@@ -37,5 +37,11 @@
   "**/tests/**/*.elm",
   "**/vendor/**/*.{jsonnet,libsonnet}",
   "**/test/**/*.zig",
-  "**/*_test.zig"
+  "**/*_test.zig",
+  "**/kitex_gen/**/*.go",
+  "**/*.capnp.h",
+  "**/*.capnp.go",
+  "**/*.capnp.ts",
+  "**/*_capnp.rs",
+  "**/*_capnp.py"
 ]
diff --git a/internal/config/allowlist/supported_file_types.json b/internal/config/allowlist/supported_file_types.json
index 08741af84..ee7ebf778 100644
--- a/internal/config/allowlist/supported_file_types.json
+++ b/internal/config/allowlist/supported_file_types.json
@@ -91,5 +91,7 @@
   ".pot",
   ".jsonnet",
   ".libsonnet",
-  ".zig"
+  ".zig",
+  ".thrift",
+  ".capnp"
 ]
diff --git a/internal/config/rules/rule_docs/capnp.md b/internal/config/rules/rule_docs/capnp.md
new file mode 100644
index 000000000..f32e7ebe7
--- /dev/null
+++ b/internal/config/rules/rule_docs/capnp.md
@@ -0,0 +1,36 @@
+> Favor precision over recall: only raise an issue when you are confident it is a real defect, and stay silent when the surrounding context is unclear — a false alarm costs more reviewer trust than a missed minor issue. Treat wire-compatibility breaks as blocking, and naming or layout preferences as non-blocking.
+
+#### Ordinals and Wire Compatibility
+- Changing the `@N` ordinal of an existing field or method; the ordinal is that member's fixed slot, so it is the one thing that must never move
+- Filling an ordinal left behind by a removed member instead of holding it with an `obsolete`/`obsoleteN` placeholder of the original width (`obsoleteSave @7 :AnyPointer`, `obsolete3 @3 :Bool`)
+- Deleting a member outright rather than renaming it to `obsolete*` and leaving its ordinal and type in place
+- Adding a member at an ordinal already used elsewhere in the same struct, union, or interface
+- Do not report a rename that leaves the ordinal alone; names are not on the wire, so renaming is free
+- Do not report declaration order that disagrees with ordinal order, which is legal and common (`rpc.capnp` declares `disembargo @13` above `obsoleteSave @7`)
+
+#### Types and Defaults
+- Widening a fixed-width field, such as `UInt32` to `UInt64` or `Float32` to `Float64`: slots are fixed-width at fixed offsets, so this is a break, unlike widening a protobuf varint
+- Any other change to an existing field's type, including a signedness flip or swapping an enum for the integer that backs it
+- Changing the default value of an existing field; Cap'n Proto encodes values XOR the default, so the same bytes decode differently on either side of the change
+- `Text` used to carry arbitrary bytes where `Data` is meant, since `Text` asserts NUL-terminated UTF-8 and readers may validate it
+- Do not report a field appended at the next unused ordinal, which is backward compatible
+
+#### Unions, Groups, and Type IDs
+- Moving an existing field into or out of a union or group, with one legal exception: wrapping an existing field in a brand-new union where it is the first member
+- A union whose lowest ordinal is not a `Void` sentinel, leaving no representable "unset" state
+- Adding a member to an existing union without confirming readers handle an unknown discriminant; older code sees a value outside the enum it was compiled against
+- Renaming a struct, interface, or file with no explicit `@0x...` id pinned: the id is derived from the name, so the rename silently changes it and breaks anything holding the old one
+- Do not report an explicit `@0x...` id carried through a rename; that is the fix, not the defect
+
+#### Interfaces and Methods
+- Renumbering an existing method, or reusing the ordinal of one that was removed
+- Changing an existing method's parameter or result struct in any way the field rules above forbid
+- Removing a method rather than renaming it to `obsolete*` and keeping the ordinal (`sandstorm` keeps `obsoleteHttpGet @1` and `obsoleteGetGrainSize @3`)
+- Capabilities returned with no documented lifetime, where dropping the client silently cancels work still in progress
+- Do not report a method rename that keeps its ordinal
+
+#### Security and Resource Limits
+- `AnyPointer` accepted from untrusted input and cast without a type check
+- Unbounded `List`, `Text`, or `Data` from untrusted input with no traversal limit or nesting limit set on the reader
+- Secrets, tokens, or credentials embedded in constants, defaults, or comments
+- Do not report when reader limits are set at the call site and that boundary is clearly documented
diff --git a/internal/config/rules/rule_docs/thrift.md b/internal/config/rules/rule_docs/thrift.md
new file mode 100644
index 000000000..c144573c4
--- /dev/null
+++ b/internal/config/rules/rule_docs/thrift.md
@@ -0,0 +1,35 @@
+> Favor precision over recall: only raise an issue when you are confident it is a real defect, and stay silent when the surrounding context is unclear — a false alarm costs more reviewer trust than a missed minor issue. Treat wire-compatibility breaks as blocking, and naming or layout preferences as non-blocking.
+
+#### Field IDs and Wire Compatibility
+- Reusing the id of a deleted field; Thrift has no `reserved` keyword, so a retired id must be held open by a placeholder field carrying a "do not reuse this id" comment
+- Renumbering an existing field, or inserting a new field by shifting the ids of everything after it, instead of appending the next unused id
+- Changing the declared type of an existing id, including `i32` to `i64` and swapping an enum for the integer that backs it; the type byte travels in the field header
+- Deleting a field that peers still send without leaving its id held open for the same reason
+- Do not report purely additive fields that take a fresh unused id, comment-only edits, or `namespace` and `include` changes
+
+#### Requiredness and Defaults
+- Adding a `required` field to an existing struct: `required` is permanent and unskippable, so every existing peer fails to deserialize in both directions the moment one side adopts it
+- Flipping an existing field between `required` and `optional`, which changes what a peer is allowed to omit
+- Changing the default value of an existing optional field; an unset field and a field holding the default are indistinguishable to the peer, so the change lands silently
+- Fields left with default requiredness where absence must be distinguishable from the zero value
+- Do not report the choice of default requiredness itself when the file is internally consistent
+
+#### Services and Methods
+- Renaming a service method: method names travel on the wire in `TMessageBegin`, unlike field names, so a rename breaks every existing caller
+- Changing the ids of an existing method's parameters, or adding a parameter declared `required`
+- Adding an exception to an existing `throws` clause that older clients have no branch to decode
+- Changing a method to or from `oneway`, which changes whether the caller waits for a reply at all
+- Do not report new methods appended to an existing service; those are backward compatible
+
+#### Enums and Constants
+- Enum members declared without explicit numeric values, which makes every value positional and shifts them all on the first insertion
+- Inserting a new enum member into the middle of an existing numeric range instead of appending
+- Code that treats an unknown enum value as unreachable; peers on a newer schema will send values this build has never seen
+- Do not report enum members appended with new explicit values
+
+#### Security and Resource Limits
+- Unbounded `list`, `set`, `map`, `string`, or `binary` fields carried over an untrusted transport with no application-level size limit
+- Recursive struct definitions with no documented depth bound on untrusted input
+- Secrets, tokens, or credentials embedded in constants, default values, or comments
+- `string` used to carry non-UTF-8 bytes where `binary` is meant, at a boundary that validates neither
+- Do not report when limits are enforced by transport or server configuration and that boundary is clearly documented
diff --git a/internal/config/rules/system_rules.json b/internal/config/rules/system_rules.json
index 14af6d445..5aeabf13d 100644
--- a/internal/config/rules/system_rules.json
+++ b/internal/config/rules/system_rules.json
@@ -39,6 +39,8 @@
     "**/*.swift": "swift.md",
     "**/*.elm": "elm.md",
     "**/*.{jsonnet,libsonnet}": "jsonnet.md",
-    "**/*.zig": "zig.md"
+    "**/*.zig": "zig.md",
+    "**/*.thrift": "thrift.md",
+    "**/*.capnp": "capnp.md"
   }
 }
diff --git a/internal/config/rules/system_rules_test.go b/internal/config/rules/system_rules_test.go
index 8f5fdc25e..f75d157a9 100644
--- a/internal/config/rules/system_rules_test.go
+++ b/internal/config/rules/system_rules_test.go
@@ -129,6 +129,10 @@ func TestResolve_DefaultRules(t *testing.T) {
 		{"analysis/plots.r", "R Code Review Principles"},
 		{"src/main.zig", "Illegal Behavior"},
 		{"build.zig", "Illegal Behavior"},
+		{"idl/service.thrift", "Field IDs and Wire Compatibility"},
+		{"if/common.thrift", "Field IDs and Wire Compatibility"},
+		{"schema/addressbook.capnp", "Ordinals and Wire Compatibility"},
+		{"src/rpc.capnp", "Ordinals and Wire Compatibility"},
 	}
 
 	for _, tt := range tests {
diff --git a/pages/src/content/docs/en/review-rules.md b/pages/src/content/docs/en/review-rules.md
index f67d5dc20..f9ed1de89 100644
--- a/pages/src/content/docs/en/review-rules.md
+++ b/pages/src/content/docs/en/review-rules.md
@@ -180,6 +180,8 @@ matching order:
 | `**/*.bicep` | `bicep.md` — Bicep (Azure) templates. |
 | `**/*.elm` | `elm.md` - Elm source. |
 | `**/*.{jsonnet,libsonnet}` | `jsonnet.md` — Jsonnet configuration templates and libraries. |
+| `**/*.thrift` | `thrift.md` — Apache Thrift IDL wire compatibility. |
+| `**/*.capnp` | `capnp.md` — Cap'n Proto schema wire compatibility. |
 | *(fallback)* | `default.md` |
 
 The resolved rule body becomes the `{{system_rule}}` placeholder in the
diff --git a/pages/src/content/docs/ja/review-rules.md b/pages/src/content/docs/ja/review-rules.md
index c35ea98b5..92108867a 100644
--- a/pages/src/content/docs/ja/review-rules.md
+++ b/pages/src/content/docs/ja/review-rules.md
@@ -142,6 +142,8 @@ OCR は [`bmatcuk/doublestar/v4`](https://pkg.go.dev/github.com/bmatcuk/doublest
 | `**/*.bicep` | `bicep.md`: Bicep（Azure）テンプレート。 |
 | `**/*.elm` | `elm.md` - Elm ソースコード。 |
 | `**/*.{jsonnet,libsonnet}` | `jsonnet.md`: Jsonnet の設定テンプレートとライブラリ。 |
+| `**/*.thrift` | `thrift.md`: Apache Thrift IDL のワイヤ互換性。 |
+| `**/*.capnp` | `capnp.md`: Cap'n Proto スキーマのワイヤ互換性。 |
 | *(fallback)* | `default.md` |
 
 解決されたルール本文は、plan および main task prompt 内の `{{system_rule}}` プレースホルダーの内容になります。
diff --git a/pages/src/content/docs/ru/review-rules.md b/pages/src/content/docs/ru/review-rules.md
index 68c7b54b3..92fa3a58e 100644
--- a/pages/src/content/docs/ru/review-rules.md
+++ b/pages/src/content/docs/ru/review-rules.md
@@ -182,6 +182,8 @@ OCR использует [`bmatcuk/doublestar/v4`](https://pkg.go.dev/github.com
 | `**/*.bicep` | `bicep.md` — шаблоны Bicep (Azure). |
 | `**/*.elm` | `elm.md` - исходный код Elm. |
 | `**/*.{jsonnet,libsonnet}` | `jsonnet.md` — шаблоны конфигурации и библиотеки Jsonnet. |
+| `**/*.thrift` | `thrift.md` — совместимость Apache Thrift IDL на уровне wire. |
+| `**/*.capnp` | `capnp.md` — совместимость схем Cap'n Proto на уровне wire. |
 | *(fallback)* | `default.md` |
 
 Разрешённое тело правила становится значением плейсхолдера `{{system_rule}}`
diff --git a/pages/src/content/docs/zh/review-rules.md b/pages/src/content/docs/zh/review-rules.md
index 5f6d94f83..e9be014b2 100644
--- a/pages/src/content/docs/zh/review-rules.md
+++ b/pages/src/content/docs/zh/review-rules.md
@@ -163,6 +163,8 @@ OCR 用 [`bmatcuk/doublestar/v4`](https://pkg.go.dev/github.com/bmatcuk/doublest
 | `**/*.bicep` | `bicep.md`——Bicep（Azure）模板。 |
 | `**/*.elm` | `elm.md` - Elm 源代码。 |
 | `**/*.{jsonnet,libsonnet}` | `jsonnet.md`——Jsonnet 配置模板与库。 |
+| `**/*.thrift` | `thrift.md`——Apache Thrift IDL 线协议兼容性。 |
+| `**/*.capnp` | `capnp.md`——Cap'n Proto schema 线协议兼容性。 |
 | *(fallback)* | `default.md` |
 
 解析出的规则正文成为 plan 和 main task prompt 中 `{{system_rule}}` 占位符的内容。