diff --git a/.claude/CLAUDE.md b/.claude/CLAUDE.md
index e698ff6e..a38ba5b6 100644
--- a/.claude/CLAUDE.md
+++ b/.claude/CLAUDE.md
@@ -18,6 +18,7 @@ Makefile は `nix develop --command bash -c "..."` でラップ済み。AI は
 |---|---|
 | CI 相当一括 | `make ci` （= `lint + test + build-web`） |
 | Backend lint | `make lint-backend` |
+| Backend 型チェック | `make typecheck-backend` （pyright。`make lint` に含まれる） |
 | Backend test | `make test-backend` |
 | Frontend lint | `make lint-web` |
 | Frontend test | `make test-web` |
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index ec4ca337..98b59e41 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -193,6 +193,13 @@ jobs:
         working-directory: backend
         run: uv run ruff check app tests alembic_migrations
 
+      # 型チェック（pyright）。pyright は pyproject [tool.pyright] の venv=".venv" を参照するため、
+      # 直前の uv pip install で .venv に依存が入っている必要がある（このジョブで担保済み）。
+      # バージョンは Makefile の typecheck-backend と揃えてピン留めする（ローカル/CI の drift 防止）。
+      - name: Type check backend (pyright)
+        working-directory: backend
+        run: uvx pyright@1.1.411 app tests alembic_migrations
+
       - name: Run backend tests
         working-directory: backend
         run: uv run pytest -q tests
diff --git a/Makefile b/Makefile
index 12dd3dd8..013f8f2a 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,7 @@
 	setup install-hooks install-backend install-web generate-keys \
 	dev dev-build dev-down dev-amd64 dev-amd64-build dev-web preview-web dev-proxy dev-proxy-only stripe-webhook \
 	test test-backend test-web \
-	lint lint-backend lint-web lint-web-messages lint-env-keys lint-fix \
+	lint lint-backend typecheck-backend lint-web lint-web-messages lint-env-keys lint-fix \
 	format format-check \
 	ci \
 	dupe-check dupe-check-html dupe-clean \
@@ -40,6 +40,7 @@ help:
 	@echo "  test-web     Frontend: vitest"
 	@echo "  lint              全リント (backend + web)"
 	@echo "  lint-backend      Backend: ruff check"
+	@echo "  typecheck-backend Backend: pyright 型チェック"
 	@echo "  lint-web     Frontend: eslint"
 	@echo "  lint-web-messages  Frontend: setError等にリテラル日本語が渡っていないか検知"
 	@echo "  lint-env-keys     env名/エラーコードの SSoT drift を検知 (env_keys.py↔compose, errors.py↔errorCodes.ts)"
@@ -141,11 +142,17 @@ test-backend:
 test-web:
 	nix develop --command bash -c "cd web && npm test"
 
-lint: lint-backend lint-web lint-web-messages lint-env-keys
+lint: lint-backend typecheck-backend lint-web lint-web-messages lint-env-keys
 
 lint-backend:
 	nix develop --command bash -c "cd backend && .venv/bin/python -m ruff check app tests alembic_migrations"
 
+# Backend 型チェック（pyright）。pyproject [tool.pyright] の venv=".venv" を参照するため
+# 事前に make install-backend で backend/.venv に依存を入れておくこと。
+# バージョンは CI（.github/workflows/test.yml）と揃えてピン留めする（drift 防止）。
+typecheck-backend:
+	nix develop --command bash -c "cd backend && uvx pyright@1.1.411 app tests alembic_migrations"
+
 lint-web:
 	nix develop --command bash -c "cd web && npm run lint"
 
diff --git a/backend/app/core/settings.py b/backend/app/core/settings.py
index abfb78f7..6f64884c 100644
--- a/backend/app/core/settings.py
+++ b/backend/app/core/settings.py
@@ -1,4 +1,5 @@
 import os
+from typing import Literal, cast
 from urllib.parse import urlparse
 
 from . import env_keys
@@ -93,7 +94,7 @@ def get_cookie_secure() -> bool:
     return True
 
 
-def get_cookie_samesite() -> str:
+def get_cookie_samesite() -> Literal["lax", "strict", "none"]:
     default = "lax"
     origins = get_cors_origins()
     if origins and not all(_is_loopback_origin(origin) for origin in origins):
@@ -102,7 +103,8 @@ def get_cookie_samesite() -> str:
     value = os.getenv(env_keys.COOKIE_SAMESITE, default).strip().lower()
     if value not in {"lax", "strict", "none"}:
         raise RuntimeError("COOKIE_SAMESITE must be one of: lax, strict, none")
-    return value
+    # 上の検証で値域は保証済み。set_cookie の samesite 引数が要求する Literal へ絞る。
+    return cast(Literal["lax", "strict", "none"], value)
 
 
 def get_admin_token() -> str:
diff --git a/backend/app/repositories/master_data.py b/backend/app/repositories/master_data.py
index 17591380..f8501a77 100644
--- a/backend/app/repositories/master_data.py
+++ b/backend/app/repositories/master_data.py
@@ -23,14 +23,17 @@ def list_by_category(self, category: str) -> list[MTechnologyStack]:
         )
         return list(self.db.scalars(statement).all())
 
-    def create(self, category: str, name: str, sort_order: int = 0) -> MTechnologyStack:
+    # category 列を持つため基底の create/update をあえて拡張シグネチャで上書きする。
+    # MTechnologyStackRepository 型で直接呼ぶ箇所のみが使い、基底経由の多態呼び出しは無いため
+    # Liskov 非互換は意図的（reportIncompatibleMethodOverride を局所抑制）。
+    def create(self, category: str, name: str, sort_order: int = 0) -> MTechnologyStack:  # pyright: ignore[reportIncompatibleMethodOverride]
         item = MTechnologyStack(category=category, name=name, sort_order=sort_order)
         self.db.add(item)
         self.db.commit()
         self.db.refresh(item)
         return item
 
-    def update(
+    def update(  # pyright: ignore[reportIncompatibleMethodOverride]
         self, item_id: str, category: str, name: str, sort_order: int = 0
     ) -> MTechnologyStack | None:
         item = self.db.scalar(select(MTechnologyStack).where(MTechnologyStack.id == item_id))
diff --git a/backend/app/repositories/notification.py b/backend/app/repositories/notification.py
index 3182f5fd..1ff641b9 100644
--- a/backend/app/repositories/notification.py
+++ b/backend/app/repositories/notification.py
@@ -1,6 +1,9 @@
 """通知リポジトリ。"""
 
+from typing import Any, cast
+
 from sqlalchemy import select, update
+from sqlalchemy.engine import CursorResult
 from sqlalchemy.orm import Session
 
 from ..models.notification import Notification
@@ -41,7 +44,7 @@ def mark_read(self, notification_id: str) -> bool:
             .where(Notification.id == notification_id, Notification.user_id == self.user_id)
             .values(is_read=True)
         )
-        result = self.db.execute(stmt)
+        result = cast("CursorResult[Any]", self.db.execute(stmt))
         self.db.commit()
         return result.rowcount > 0
 
@@ -52,7 +55,7 @@ def mark_all_read(self) -> int:
             .where(Notification.user_id == self.user_id, Notification.is_read.is_(False))
             .values(is_read=True)
         )
-        result = self.db.execute(stmt)
+        result = cast("CursorResult[Any]", self.db.execute(stmt))
         self.db.commit()
         return result.rowcount
 
diff --git a/backend/app/repositories/resume.py b/backend/app/repositories/resume.py
index e13e74d9..916af584 100644
--- a/backend/app/repositories/resume.py
+++ b/backend/app/repositories/resume.py
@@ -1,3 +1,5 @@
+from typing import Any
+
 from sqlalchemy.orm import selectinload
 
 from ..core.date_utils import parse_year_month
@@ -39,7 +41,7 @@ class ResumeRepository(SingleUserDocumentRepository):
         selectinload(Resume.qualification_rows),
     )
 
-    def _apply_payload(self, entity: Resume, payload: dict[str, object]) -> None:
+    def _apply_payload(self, entity: Resume, payload: dict[str, Any]) -> None:
         entity.full_name = payload["full_name"]
         entity.email = payload["email"]
         entity.github_url = payload.get("github_url", "")
@@ -67,7 +69,7 @@ def _apply_payload(self, entity: Resume, payload: dict[str, object]) -> None:
             for index, item in enumerate(sorted_qualifications)
         ]
 
-    def _build_experience_row(self, index: int, payload: dict[str, object]) -> ResumeExperience:
+    def _build_experience_row(self, index: int, payload: dict[str, Any]) -> ResumeExperience:
         return ResumeExperience(
             sort_order=index,
             company=payload["company"],
@@ -88,7 +90,7 @@ def _build_experience_row(self, index: int, payload: dict[str, object]) -> Resum
             ],
         )
 
-    def _build_client_row(self, index: int, payload: dict[str, object]) -> ResumeClient:
+    def _build_client_row(self, index: int, payload: dict[str, Any]) -> ResumeClient:
         projects = list(payload.get("projects", []))
         sorted_projects = sorted(projects, key=self._project_sort_key)
         vacation_start = payload.get("vacation_start_date") or ""
@@ -109,7 +111,7 @@ def _build_client_row(self, index: int, payload: dict[str, object]) -> ResumeCli
         )
 
     @staticmethod
-    def _project_sort_key(proj: dict[str, object]) -> tuple:
+    def _project_sort_key(proj: dict[str, Any]) -> tuple:
         """複数期間を持つプロジェクトを sort_by_period_desc と同じ降順ロジックでソートする。"""
         from datetime import date as _date
 
@@ -131,10 +133,10 @@ def _parse(val: object) -> _date | None:
         if is_any_current:
             return (0, _date.max - effective_start)
         ends = [_parse(p.get("end_date")) for p in periods if p.get("end_date")]
-        effective_end = max(ends, default=_date.min)
+        effective_end = max((e for e in ends if e), default=_date.min)
         return (1, _date.max - effective_end, _date.max - effective_start)
 
-    def _build_project_row(self, index: int, payload: dict[str, object]) -> ResumeProject:
+    def _build_project_row(self, index: int, payload: dict[str, Any]) -> ResumeProject:
         team = payload.get("team", {})
         periods = list(payload.get("periods", []))
         return ResumeProject(
diff --git a/backend/app/routers/blog/accounts.py b/backend/app/routers/blog/accounts.py
index 250a6de5..11643148 100644
--- a/backend/app/routers/blog/accounts.py
+++ b/backend/app/routers/blog/accounts.py
@@ -75,11 +75,6 @@ async def add_account(
             status_code=502,
             detail=get_error("blog.account_check_failed"),
         ) from exc
-    except BlogAccountNotFoundError as exc:
-        raise HTTPException(
-            status_code=404,
-            detail=get_error("blog.account_not_found"),
-        ) from exc
 
 
 @router.patch("/accounts/{platform}", response_model=BlogAccountResponse)
diff --git a/backend/app/routers/github_link/endpoints.py b/backend/app/routers/github_link/endpoints.py
index d08fec7a..8a0c04a2 100644
--- a/backend/app/routers/github_link/endpoints.py
+++ b/backend/app/routers/github_link/endpoints.py
@@ -22,6 +22,7 @@
 from ...schemas.github_link import (
     CachedGitHubLinkResponse,
     GitHubLinkRequest,
+    GitHubLinkResponse,
     ProgressResponse,
 )
 from ...schemas.github_skill import GitHubSkillsResponse
@@ -69,8 +70,13 @@ def get_cache(
     cache = GitHubLinkCacheRepository(db).get_by_user(user.id)
     if not cache:
         return CachedGitHubLinkResponse()
+    # cache.result は GitHubLinkResponse(...).model_dump() を保存した JSON（dict | None）。
+    # Pydantic v2 は dict を受け取ると検証済みモデルへコアース可能なので validate で型を絞る。
+    result = (
+        GitHubLinkResponse.model_validate(cache.result) if cache.result is not None else None
+    )
     return CachedGitHubLinkResponse(
-        result=cache.result,
+        result=result,
         status=cache.status,
         error_message=cache.error_message,
         error_code=resolve_async_error_code(cache.error_message),
diff --git a/backend/app/services/agent/chat_service.py b/backend/app/services/agent/chat_service.py
index 0d2af8ef..7d4c9b64 100644
--- a/backend/app/services/agent/chat_service.py
+++ b/backend/app/services/agent/chat_service.py
@@ -21,6 +21,7 @@
     AgentOperation,
     AgentProjectContext,
     ExperienceTarget,
+    ProjectTarget,
 )
 from .llm.base import LLMError
 from .llm.factory import get_llm_client
@@ -193,8 +194,8 @@ def _resolve_target_experience(request: AgentChatRequest) -> AgentExperienceCont
 def _resolve_target_project(request: AgentChatRequest) -> AgentProjectContext:
     """target のインデックスから対象プロジェクトを取り出す。範囲外は専用例外。"""
     target = request.target
-    # scope=project のとき target は schema で必須検証済み
-    assert target is not None
+    # scope=project のとき target は schema で ProjectTarget（client_index/project_index 必須）に検証済み
+    assert isinstance(target, ProjectTarget)
     try:
         return (
             request.resume.experiences[target.experience_index]
diff --git a/backend/app/services/agent/llm/anthropic_client.py b/backend/app/services/agent/llm/anthropic_client.py
index 8cb71992..5623da8b 100644
--- a/backend/app/services/agent/llm/anthropic_client.py
+++ b/backend/app/services/agent/llm/anthropic_client.py
@@ -6,9 +6,10 @@
 """
 
 import json
+from typing import Any, cast
 
 import anthropic
-from anthropic import AsyncAnthropicVertex
+from anthropic import AsyncAnthropicVertex  # pyright: ignore[reportPrivateImportUsage]
 
 from ....core import settings
 from ..output_schema import TOOL_NAME, build_tool_definition
@@ -47,10 +48,11 @@ async def generate(
                 max_tokens=_MAX_TOKENS,
                 temperature=_TEMPERATURE,
                 system=system_prompt,
-                messages=messages,
+                # 履歴契約の dict 形は SDK の MessageParam と互換だが静的には別型のため境界で cast。
+                messages=cast(Any, messages),
                 # tool use 強制で出力構造をスキーマに従わせる（JSON mode は使わない）。
                 # maxLength は API では強制されないため、上限超過は呼び出し側で破棄する
-                tools=[build_tool_definition(output_schema)],
+                tools=[cast(Any, build_tool_definition(output_schema))],
                 tool_choice={"type": "tool", "name": TOOL_NAME},
             )
         except (
diff --git a/backend/app/services/agent/llm/google_client.py b/backend/app/services/agent/llm/google_client.py
index a7e125ba..6f93335f 100644
--- a/backend/app/services/agent/llm/google_client.py
+++ b/backend/app/services/agent/llm/google_client.py
@@ -7,6 +7,8 @@
 スキーマに従う JSON のシリアライズ文字列として返す。
 """
 
+from typing import Any, cast
+
 from google import genai
 from google.genai import errors as genai_errors
 from google.genai import types as genai_types
@@ -59,7 +61,8 @@ async def generate(
         )
         try:
             response = await self._client.aio.models.generate_content(
-                model=model_id, contents=contents, config=config
+                # list[Content] は ContentListUnion に含まれるが静的には別型のため境界で cast。
+                model=model_id, contents=cast(Any, contents), config=config
             )
         except genai_errors.APIError as exc:
             raise wrap_api_error("Google", exc) from exc
diff --git a/backend/app/services/agent/llm/openai_client.py b/backend/app/services/agent/llm/openai_client.py
index 09608caf..c22ad359 100644
--- a/backend/app/services/agent/llm/openai_client.py
+++ b/backend/app/services/agent/llm/openai_client.py
@@ -5,6 +5,8 @@
 応答テキストは Anthropic / Gemini と同じくスキーマに従う JSON のシリアライズ文字列で返す。
 """
 
+from typing import Any, cast
+
 import openai
 
 from ....core import settings
@@ -37,7 +39,8 @@ async def generate(
             response = await self._client.chat.completions.create(
                 model=model_id,
                 temperature=_TEMPERATURE,
-                messages=full_messages,
+                # role/content の dict 形は SDK の ChatCompletionMessageParam と互換だが静的には別型。
+                messages=cast(Any, full_messages),
                 response_format={
                     "type": "json_schema",
                     "json_schema": {
diff --git a/backend/app/services/agent/output_schema.py b/backend/app/services/agent/output_schema.py
index ec66b08f..b4884b23 100644
--- a/backend/app/services/agent/output_schema.py
+++ b/backend/app/services/agent/output_schema.py
@@ -12,6 +12,8 @@
 maxLength は JSON Schema 仕様どおり Unicode 文字数（日本語の len() と一致）。
 """
 
+from typing import cast
+
 TOOL_NAME = "propose_revision"
 TOOL_DESCRIPTION = "職務経歴書フィールドの改善案・説明・次の依頼候補を返す"
 
@@ -103,7 +105,8 @@ def to_portable_schema(schema: dict, *, drop_additional_properties: bool = False
     strip_keys = {"maxLength", "maxItems"}
     if drop_additional_properties:
         strip_keys = strip_keys | {"additionalProperties"}
-    portable = _strip_constraints(schema, strip_keys)
+    # _strip_constraints は object を返すが、dict 入力に対しては dict を返す（下で .get / 返却に使う）。
+    portable = cast(dict, _strip_constraints(schema, strip_keys))
     operations = portable.get("properties", {}).get("operations", {})
     items = operations.get("items", {})
     branches = items.get("oneOf")
diff --git a/backend/app/services/intelligence/skills/imports/go.py b/backend/app/services/intelligence/skills/imports/go.py
index dbf72347..a9ac1339 100644
--- a/backend/app/services/intelligence/skills/imports/go.py
+++ b/backend/app/services/intelligence/skills/imports/go.py
@@ -17,8 +17,8 @@
 
 
 class GoImportScanner:
-    extensions = (".go",)
-    ecosystem = "go"
+    extensions: tuple[str, ...] = (".go",)
+    ecosystem: str = "go"
 
     def scan(self, content: str) -> set[str]:
         paths: set[str] = set()
diff --git a/backend/app/services/intelligence/skills/imports/js_ts.py b/backend/app/services/intelligence/skills/imports/js_ts.py
index 90439958..d5848f29 100644
--- a/backend/app/services/intelligence/skills/imports/js_ts.py
+++ b/backend/app/services/intelligence/skills/imports/js_ts.py
@@ -42,8 +42,17 @@ def _package_of(spec: str) -> str | None:
 
 
 class JsTsImportScanner:
-    extensions = (".js", ".jsx", ".ts", ".tsx", ".mjs", ".cjs", ".mts", ".cts")
-    ecosystem = "npm"
+    extensions: tuple[str, ...] = (
+        ".js",
+        ".jsx",
+        ".ts",
+        ".tsx",
+        ".mjs",
+        ".cjs",
+        ".mts",
+        ".cts",
+    )
+    ecosystem: str = "npm"
 
     def scan(self, content: str) -> set[str]:
         names: set[str] = set()
diff --git a/backend/app/services/intelligence/skills/imports/python.py b/backend/app/services/intelligence/skills/imports/python.py
index 58dc751a..e3e855ce 100644
--- a/backend/app/services/intelligence/skills/imports/python.py
+++ b/backend/app/services/intelligence/skills/imports/python.py
@@ -20,8 +20,8 @@ def _top_level(module: str) -> str:
 
 
 class PythonImportScanner:
-    extensions = (".py", ".pyi")
-    ecosystem = "pypi"
+    extensions: tuple[str, ...] = (".py", ".pyi")
+    ecosystem: str = "pypi"
 
     def scan(self, content: str) -> set[str]:
         return {_top_level(m) for m in _IMPORT_RE.findall(content)}
diff --git a/backend/app/services/intelligence/skills/imports/rust.py b/backend/app/services/intelligence/skills/imports/rust.py
index 7660ad7c..596876e9 100644
--- a/backend/app/services/intelligence/skills/imports/rust.py
+++ b/backend/app/services/intelligence/skills/imports/rust.py
@@ -20,8 +20,8 @@
 
 
 class RustImportScanner:
-    extensions = (".rs",)
-    ecosystem = "cargo"
+    extensions: tuple[str, ...] = (".rs",)
+    ecosystem: str = "cargo"
 
     def scan(self, content: str) -> set[str]:
         names = set(_USE_RE.findall(content)) | set(_EXTERN_RE.findall(content))
diff --git a/backend/app/services/intelligence/skills/manifests/cargo_toml.py b/backend/app/services/intelligence/skills/manifests/cargo_toml.py
index da88be2c..79ce7b64 100644
--- a/backend/app/services/intelligence/skills/manifests/cargo_toml.py
+++ b/backend/app/services/intelligence/skills/manifests/cargo_toml.py
@@ -16,8 +16,8 @@
 
 
 class CargoTomlParser:
-    filenames = ("Cargo.toml",)
-    ecosystem = "cargo"
+    filenames: tuple[str, ...] = ("Cargo.toml",)
+    ecosystem: str = "cargo"
 
     def parse(self, content: str) -> list[PackageDeclaration]:
         try:
diff --git a/backend/app/services/intelligence/skills/manifests/go_mod.py b/backend/app/services/intelligence/skills/manifests/go_mod.py
index 3fdf4fde..055a9b4f 100644
--- a/backend/app/services/intelligence/skills/manifests/go_mod.py
+++ b/backend/app/services/intelligence/skills/manifests/go_mod.py
@@ -15,8 +15,8 @@
 
 
 class GoModParser:
-    filenames = ("go.mod",)
-    ecosystem = "go"
+    filenames: tuple[str, ...] = ("go.mod",)
+    ecosystem: str = "go"
 
     def parse(self, content: str) -> list[PackageDeclaration]:
         declarations: list[PackageDeclaration] = []
diff --git a/backend/app/services/intelligence/skills/manifests/package_json.py b/backend/app/services/intelligence/skills/manifests/package_json.py
index e8e3290c..799e812d 100644
--- a/backend/app/services/intelligence/skills/manifests/package_json.py
+++ b/backend/app/services/intelligence/skills/manifests/package_json.py
@@ -19,8 +19,8 @@
 
 
 class PackageJsonParser:
-    filenames = ("package.json",)
-    ecosystem = "npm"
+    filenames: tuple[str, ...] = ("package.json",)
+    ecosystem: str = "npm"
 
     def parse(self, content: str) -> list[PackageDeclaration]:
         try:
diff --git a/backend/app/services/intelligence/skills/manifests/pyproject.py b/backend/app/services/intelligence/skills/manifests/pyproject.py
index df17bc99..b59a3fde 100644
--- a/backend/app/services/intelligence/skills/manifests/pyproject.py
+++ b/backend/app/services/intelligence/skills/manifests/pyproject.py
@@ -18,8 +18,8 @@
 
 
 class PyprojectParser:
-    filenames = ("pyproject.toml",)
-    ecosystem = "pypi"
+    filenames: tuple[str, ...] = ("pyproject.toml",)
+    ecosystem: str = "pypi"
 
     def parse(self, content: str) -> list[PackageDeclaration]:
         try:
diff --git a/backend/app/services/intelligence/skills/manifests/requirements_txt.py b/backend/app/services/intelligence/skills/manifests/requirements_txt.py
index 4a6f1c73..7e892d3b 100644
--- a/backend/app/services/intelligence/skills/manifests/requirements_txt.py
+++ b/backend/app/services/intelligence/skills/manifests/requirements_txt.py
@@ -9,8 +9,8 @@
 
 
 class RequirementsTxtParser:
-    filenames = ("requirements.txt",)
-    ecosystem = "pypi"
+    filenames: tuple[str, ...] = ("requirements.txt",)
+    ecosystem: str = "pypi"
 
     def parse(self, content: str) -> list[PackageDeclaration]:
         declarations: list[PackageDeclaration] = []
diff --git a/backend/app/services/pdf/generators/resume_generator.py b/backend/app/services/pdf/generators/resume_generator.py
index 4e967b67..9c7f1857 100644
--- a/backend/app/services/pdf/generators/resume_generator.py
+++ b/backend/app/services/pdf/generators/resume_generator.py
@@ -391,5 +391,8 @@ def build_resume_pdf(resume: dict) -> bytes:
         f"</head><body>{html_body}</body></html>"
     )
 
+    # target 未指定の write_pdf は bytes を返す（None は出力先を渡したときのみ）。
     pdf_bytes = weasyprint.HTML(string=full_html).write_pdf()
+    if pdf_bytes is None:
+        raise RuntimeError("PDF の生成に失敗しました")
     return pdf_bytes
diff --git a/backend/tests/blog/test_accounts.py b/backend/tests/blog/test_accounts.py
index ca28fe8b..50e92500 100644
--- a/backend/tests/blog/test_accounts.py
+++ b/backend/tests/blog/test_accounts.py
@@ -167,6 +167,7 @@ def test_update_blog_account_resets_articles_and_sync_state(
     from app.repositories import BlogArticleRepository, UserRepository
 
     user = UserRepository(db_session).get_by_username("testuser")
+    assert user is not None
     account_repo = BlogAccountRepository(db_session, user.id)
     account = account_repo.get_by_id(account_id)
     assert account is not None
@@ -249,6 +250,7 @@ def test_list_blog_articles_returns_platform_and_tags(
     from app.repositories import BlogArticleRepository, UserRepository
 
     user = UserRepository(db_session).get_by_username("testuser")
+    assert user is not None
     repo = BlogArticleRepository(db_session, user.id)
     repo.upsert_many(
         [
diff --git a/backend/tests/blog/test_sync.py b/backend/tests/blog/test_sync.py
index deacadf0..0d7021b7 100644
--- a/backend/tests/blog/test_sync.py
+++ b/backend/tests/blog/test_sync.py
@@ -54,6 +54,7 @@ def test_sync_account_normalizes_saved_username_and_removes_stale_articles(
     from app.repositories import BlogArticleRepository, UserRepository
 
     user = UserRepository(db_session).get_by_username("testuser")
+    assert user is not None
     account = BlogAccount(
         user_id=user.id,
         platform="zenn",
@@ -125,6 +126,7 @@ def test_upsert_articles_no_duplicates(client: TestClient, db_session: Session)
     from app.repositories import BlogArticleRepository, UserRepository
 
     user = UserRepository(db_session).get_by_username("testuser")
+    assert user is not None
     repo = BlogArticleRepository(db_session, user.id)
 
     articles = [
diff --git a/backend/tests/conftest.py b/backend/tests/conftest.py
index 5a4aaab0..a68f53b7 100644
--- a/backend/tests/conftest.py
+++ b/backend/tests/conftest.py
@@ -150,7 +150,7 @@ def _override_get_db():
         module: module.execute_task for module in (_worker, _internal_router, _tasks_local)
     }
     for module in originals:
-        module.execute_task = mock_execute_task
+        setattr(module, "execute_task", mock_execute_task)
 
     limiter.reset()
     with TestClient(app) as c:
@@ -158,7 +158,7 @@ def _override_get_db():
         yield c
     app.dependency_overrides.clear()
     for module, original in originals.items():
-        module.execute_task = original
+        setattr(module, "execute_task", original)
 
 
 def make_resume_payload(**overrides) -> dict:
diff --git a/backend/tests/security/test_mass_assignment.py b/backend/tests/security/test_mass_assignment.py
index e3addd91..f0af7cef 100644
--- a/backend/tests/security/test_mass_assignment.py
+++ b/backend/tests/security/test_mass_assignment.py
@@ -20,9 +20,11 @@ def test_resume_create_does_not_transfer_ownership(client: TestClient) -> None:
     db = client._db_session
     UserRepository(db).create("victim-a", email="victim-a@example.com")
     victim = UserRepository(db).get_by_username("victim-a")
+    assert victim is not None
 
     headers = auth_header(client, "attacker-a")
     attacker = UserRepository(db).get_by_username("attacker-a")
+    assert attacker is not None
 
     payload = make_resume_payload(user_id=victim.id)
     resp = client.post("/api/resumes", json=payload, headers=headers)
@@ -41,9 +43,11 @@ def test_resume_update_does_not_transfer_ownership(client: TestClient) -> None:
     db = client._db_session
     UserRepository(db).create("victim-b", email="victim-b@example.com")
     victim = UserRepository(db).get_by_username("victim-b")
+    assert victim is not None
 
     headers = auth_header(client, "attacker-b")
     attacker = UserRepository(db).get_by_username("attacker-b")
+    assert attacker is not None
 
     created = client.post("/api/resumes", json=make_resume_payload(), headers=headers)
     assert created.status_code == 201
@@ -67,9 +71,11 @@ def test_blog_account_create_does_not_transfer_ownership(client: TestClient) ->
     db = client._db_session
     UserRepository(db).create("victim-blog-a", email="victim-blog-a@example.com")
     victim = UserRepository(db).get_by_username("victim-blog-a")
+    assert victim is not None
 
     headers = auth_header(client, "attacker-blog-a")
     attacker = UserRepository(db).get_by_username("attacker-blog-a")
+    assert attacker is not None
 
     with patch(_ACCOUNT_VERIFY_PATCH, new_callable=AsyncMock, return_value=True):
         resp = client.post(
@@ -91,9 +97,11 @@ def test_blog_account_update_does_not_transfer_ownership(client: TestClient) ->
     db = client._db_session
     UserRepository(db).create("victim-blog-b", email="victim-blog-b@example.com")
     victim = UserRepository(db).get_by_username("victim-blog-b")
+    assert victim is not None
 
     headers = auth_header(client, "attacker-blog-b")
     attacker = UserRepository(db).get_by_username("attacker-blog-b")
+    assert attacker is not None
 
     with patch(_ACCOUNT_VERIFY_PATCH, new_callable=AsyncMock, return_value=True), patch(
         _SERVICE_VERIFY_PATCH,
diff --git a/backend/tests/test_billing.py b/backend/tests/test_billing.py
index 30f5dc44..cfcfffdc 100644
--- a/backend/tests/test_billing.py
+++ b/backend/tests/test_billing.py
@@ -4,9 +4,10 @@
 実 DB（テスト用 SQLite セッション）を通す。
 """
 
-from typing import get_args
+from typing import cast, get_args
 
 import pytest
+import stripe
 from app.core import settings
 from app.models import AgentUsageLog
 from app.repositories import BillingRepository, UserRepository
@@ -759,13 +760,14 @@ def test_record_stripe_purchase_grants_once(client: TestClient) -> None:
 def test_extract_completed_purchase_skips_unpaid() -> None:
     """未払い（payment_status != paid）のイベントは付与対象にしない。"""
     event = _completed_event("u1", 1_000, payment_status="unpaid")
-    assert stripe_service.extract_completed_purchase(event) is None
+    # stripe.Event は dict ライクに振る舞う（helper は同等 dict を返す）。境界で型を合わせる。
+    assert stripe_service.extract_completed_purchase(cast(stripe.Event, event)) is None
 
 
 def test_extract_completed_purchase_skips_other_event_types() -> None:
     """checkout.session.completed 以外のイベントは付与対象にしない。"""
     event = _completed_event("u1", 1_000, event_type="payment_intent.created")
-    assert stripe_service.extract_completed_purchase(event) is None
+    assert stripe_service.extract_completed_purchase(cast(stripe.Event, event)) is None
 
 
 # --- 統合テスト（Checkout セッション作成） ---
diff --git a/backend/tests/test_database_libsql_binary.py b/backend/tests/test_database_libsql_binary.py
index ee3d7115..30e2de71 100644
--- a/backend/tests/test_database_libsql_binary.py
+++ b/backend/tests/test_database_libsql_binary.py
@@ -42,4 +42,6 @@ def test_standard_sqlite_dialect_unaffected():
     engine = create_engine("sqlite:///:memory:", poolclass=NullPool)
     assert engine.dialect.driver == "pysqlite"
     # pysqlite は標準で Binary を提供する
-    assert callable(engine.dialect.dbapi.Binary)
+    dbapi = engine.dialect.dbapi
+    assert dbapi is not None
+    assert callable(dbapi.Binary)
diff --git a/backend/tests/test_github_skills_api.py b/backend/tests/test_github_skills_api.py
index f071e09e..da75fcdb 100644
--- a/backend/tests/test_github_skills_api.py
+++ b/backend/tests/test_github_skills_api.py
@@ -9,7 +9,9 @@
 
 
 def _user_id(client, username: str) -> str:
-    return UserRepository(client._db_session).get_by_username(username).id
+    user = UserRepository(client._db_session).get_by_username(username)
+    assert user is not None
+    return user.id
 
 
 def _sample_detected() -> list[DetectedSkill]:
diff --git a/backend/tests/test_pdf_generator.py b/backend/tests/test_pdf_generator.py
index 26971e1d..05fb0a99 100644
--- a/backend/tests/test_pdf_generator.py
+++ b/backend/tests/test_pdf_generator.py
@@ -16,7 +16,8 @@
 
 
 def test_format_period_for_current() -> None:
-    period = _format_period("2022-04", None, True)
+    # 在籍中は end_date を "" で受ける契約（format_period の docstring 準拠）。
+    period = _format_period("2022-04", "", True)
     assert "現在" in period
 
 
diff --git a/backend/tests/test_retry_flow.py b/backend/tests/test_retry_flow.py
index dedbae7c..d666258a 100644
--- a/backend/tests/test_retry_flow.py
+++ b/backend/tests/test_retry_flow.py
@@ -327,6 +327,7 @@ def test_intelligence_retry_resets_cache(self, client: TestClient):
         headers = auth_header(client, "retry-intel-user", github_id=999)
         db = client._db_session
         user = UserRepository(db).get_by_username("retry-intel-user")
+        assert user is not None
 
         cache = GitHubLinkCache(
             user_id=user.id,
@@ -359,6 +360,7 @@ def test_retry_returns_409_when_not_dead_letter(self, client: TestClient, status
         headers = auth_header(client, username, github_id=999)
         db = client._db_session
         user = UserRepository(db).get_by_username(username)
+        assert user is not None
 
         cache = GitHubLinkCache(user_id=user.id, status=status)
         db.add(cache)
@@ -377,6 +379,7 @@ def test_retry_returns_409_on_concurrent_reset_race(self, client: TestClient):
         headers = auth_header(client, "retry-race-user", github_id=999)
         db = client._db_session
         user = UserRepository(db).get_by_username("retry-race-user")
+        assert user is not None
 
         cache = GitHubLinkCache(user_id=user.id, status="dead_letter", retry_count=2)
         db.add(cache)
diff --git a/backend/tests/test_schemas.py b/backend/tests/test_schemas.py
index cdee6708..9f80ab21 100644
--- a/backend/tests/test_schemas.py
+++ b/backend/tests/test_schemas.py
@@ -182,33 +182,39 @@ def test_project_requires_start_date() -> None:
     旧実装ではここを素通りし、repositories 層の parse_year_month("") で 500 になっていた。
     """
     with pytest.raises(ValidationError, match="開始年月を入力してください"):
-        Project(
-            name="API開発",
-            start_date="",
-            end_date="2024-03",
-            is_current=False,
-            technology_stacks=[],
+        Project.model_validate(
+            {
+                "name": "API開発",
+                "start_date": "",
+                "end_date": "2024-03",
+                "is_current": False,
+                "technology_stacks": [],
+            }
         )
 
 
 def test_project_requires_end_date_when_not_current() -> None:
     """プロジェクト: 参画中でなければ終了年月が必須。"""
     with pytest.raises(ValidationError, match="終了年月"):
-        Project(
-            name="API開発",
-            start_date="2021-04",
-            end_date="",
-            is_current=False,
-            technology_stacks=[],
+        Project.model_validate(
+            {
+                "name": "API開発",
+                "start_date": "2021-04",
+                "end_date": "",
+                "is_current": False,
+                "technology_stacks": [],
+            }
         )
 
 
 def test_project_current_without_end_date_is_accepted() -> None:
     """プロジェクト: 参画中（is_current=True）なら終了年月が空でも OK。"""
-    proj = Project(
-        name="API開発",
-        periods=[{"start_date": "2021-04", "end_date": "", "is_current": True}],
-        technology_stacks=[],
+    proj = Project.model_validate(
+        {
+            "name": "API開発",
+            "periods": [{"start_date": "2021-04", "end_date": "", "is_current": True}],
+            "technology_stacks": [],
+        }
     )
     assert proj.periods[0].start_date == "2021-04"
     assert proj.periods[0].end_date == ""
@@ -295,31 +301,37 @@ def test_experience_end_date_none_is_rejected() -> None:
 def test_project_end_date_before_start_date_is_rejected() -> None:
     """プロジェクト: 終了日が開始日より前の場合はエラーとなること。"""
     with pytest.raises(ValidationError, match="開始日は終了日より前"):
-        Project(
-            name="テスト",
-            start_date="2024-04",
-            end_date="2021-03",
-            is_current=False,
-            technology_stacks=[],
+        Project.model_validate(
+            {
+                "name": "テスト",
+                "start_date": "2024-04",
+                "end_date": "2021-03",
+                "is_current": False,
+                "technology_stacks": [],
+            }
         )
 
 
 def test_project_end_date_equals_start_date_is_accepted() -> None:
     """プロジェクト: 終了日 = 開始日は正常に保存されること。"""
-    proj = Project(
-        name="テスト",
-        periods=[{"start_date": "2024-04", "end_date": "2024-04", "is_current": False}],
-        technology_stacks=[],
+    proj = Project.model_validate(
+        {
+            "name": "テスト",
+            "periods": [{"start_date": "2024-04", "end_date": "2024-04", "is_current": False}],
+            "technology_stacks": [],
+        }
     )
     assert proj.periods[0].end_date == "2024-04"
 
 
 def test_project_end_date_after_start_date_is_accepted() -> None:
     """プロジェクト: 終了日 > 開始日は正常に保存されること。"""
-    proj = Project(
-        name="テスト",
-        periods=[{"start_date": "2021-04", "end_date": "2024-03", "is_current": False}],
-        technology_stacks=[],
+    proj = Project.model_validate(
+        {
+            "name": "テスト",
+            "periods": [{"start_date": "2021-04", "end_date": "2024-03", "is_current": False}],
+            "technology_stacks": [],
+        }
     )
     assert proj.periods[0].end_date == "2024-03"
 
@@ -327,18 +339,22 @@ def test_project_end_date_after_start_date_is_accepted() -> None:
 def test_project_in_progress_end_date_is_normalized_to_empty() -> None:
     """プロジェクト: 参画中（is_current=True）の期間は end_date が "" に正規化されること。"""
     # 値が入っていても is_current=True なら "" に正規化される
-    proj = Project(
-        name="テスト",
-        periods=[{"start_date": "2021-04", "end_date": "2024-03", "is_current": True}],
-        technology_stacks=[],
+    proj = Project.model_validate(
+        {
+            "name": "テスト",
+            "periods": [{"start_date": "2021-04", "end_date": "2024-03", "is_current": True}],
+            "technology_stacks": [],
+        }
     )
     assert proj.periods[0].end_date == ""
 
     # 空文字列も当然 OK
-    proj_empty = Project(
-        name="テスト",
-        periods=[{"start_date": "2021-04", "end_date": "", "is_current": True}],
-        technology_stacks=[],
+    proj_empty = Project.model_validate(
+        {
+            "name": "テスト",
+            "periods": [{"start_date": "2021-04", "end_date": "", "is_current": True}],
+            "technology_stacks": [],
+        }
     )
     assert proj_empty.periods[0].end_date == ""
 
@@ -346,12 +362,14 @@ def test_project_in_progress_end_date_is_normalized_to_empty() -> None:
 def test_project_end_date_none_is_rejected() -> None:
     """プロジェクト: end_date に None を渡すと ValidationError になる。"""
     with pytest.raises(ValidationError):
-        Project(
-            name="テスト",
-            start_date="2021-04",
-            end_date=None,
-            is_current=True,
-            technology_stacks=[],
+        Project.model_validate(
+            {
+                "name": "テスト",
+                "start_date": "2021-04",
+                "end_date": None,
+                "is_current": True,
+                "technology_stacks": [],
+            }
         )
 
 
diff --git a/backend/tests/test_skill_import_scanners.py b/backend/tests/test_skill_import_scanners.py
index 1a2d6f63..df6804bd 100644
--- a/backend/tests/test_skill_import_scanners.py
+++ b/backend/tests/test_skill_import_scanners.py
@@ -25,10 +25,15 @@ def test_source_extensions_cover_all_ecosystems():
 
 
 def test_scanner_for_extension_dispatches_by_suffix():
-    assert scanner_for_extension("a/b/main.py").ecosystem == "pypi"
-    assert scanner_for_extension("src/index.tsx").ecosystem == "npm"
-    assert scanner_for_extension("cmd/main.go").ecosystem == "go"
-    assert scanner_for_extension("src/lib.rs").ecosystem == "cargo"
+    for path, ecosystem in (
+        ("a/b/main.py", "pypi"),
+        ("src/index.tsx", "npm"),
+        ("cmd/main.go", "go"),
+        ("src/lib.rs", "cargo"),
+    ):
+        scanner = scanner_for_extension(path)
+        assert scanner is not None
+        assert scanner.ecosystem == ecosystem
     assert scanner_for_extension("README.md") is None
     assert scanner_for_extension("no_extension") is None
 
diff --git a/docs/development.md b/docs/development.md
index b39c1ea8..162f2a15 100644
--- a/docs/development.md
+++ b/docs/development.md
@@ -120,9 +120,10 @@ make ci          # lint + test + build-web
 ### バックエンド
 
 ```bash
-make lint-backend    # ruff check（app / tests / alembic_migrations）
-make test-backend    # pytest -q tests
-make lint-fix        # ruff --fix（自動修正）
+make lint-backend       # ruff check（app / tests / alembic_migrations）
+make typecheck-backend  # pyright 型チェック（make lint に含まれる）
+make test-backend       # pytest -q tests
+make lint-fix           # ruff --fix（自動修正）
 ```
 
 特定ファイルだけ ruff したい場合:
@@ -131,6 +132,8 @@ make lint-fix        # ruff --fix（自動修正）
 nix develop --command bash -c "cd backend && .venv/bin/python -m ruff check <path>"
 ```
 
+> **pyright の前提**: 型チェックは `backend/pyproject.toml` の `[tool.pyright]`（`venv=".venv"`）を参照するため、事前に `make install-backend` で `backend/.venv` へ依存を入れておくこと。バージョンは CI（`.github/workflows/test.yml`）と Makefile でピン留めを揃えている。
+
 ### フロントエンド（ユニット・ビルド）
 
 ```bash