diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2d51d03..a5cab0d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -27,8 +27,8 @@ jobs:
       - uses: Swatinem/rust-cache@v2
       - run: cargo fmt --all --check
 
-  test:
-    name: cargo test (${{ matrix.os }})
+  nextest:
+    name: nextest (${{ matrix.os }})
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
@@ -37,12 +37,14 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
-        with:
-          components: clippy
       - uses: Swatinem/rust-cache@v2
+      - uses: taiki-e/install-action@nextest
+
+      - name: Run tests with nextest
+        run: cargo nextest run --workspace --release --no-fail-fast
 
-      - name: Run tests
-        run: cargo test --workspace --release
+      - name: Run doctests
+        run: cargo test --doc --workspace --release
 
   coverage:
     name: coverage
@@ -53,9 +55,10 @@ jobs:
         with:
           components: llvm-tools-preview
       - uses: Swatinem/rust-cache@v2
+      - uses: taiki-e/install-action@nextest
       - uses: taiki-e/install-action@cargo-llvm-cov
       - name: Generate coverage JSON
-        run: cargo llvm-cov --workspace --json --output-path coverage.json
+        run: cargo llvm-cov nextest --workspace --release --json --output-path coverage.json
       - name: Check per-file thresholds
         run: python3 scripts/check-coverage.py coverage.json
 
diff --git a/AGENTS.md b/AGENTS.md
index bc0d728..c4854ff 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -51,13 +51,15 @@ When a file grows large, split it by functionality (e.g., parsing, plan computat
 **Always use `--release` mode for tests** to enable optimizations and speed up trial-and-error cycles.
 
 ```bash
-cargo test --release                    # Full suite
-cargo test --release --test test_name   # Specific test
-cargo test --release --workspace        # All crates
+cargo nextest run --release                    # Full suite
+cargo nextest run --release --test test_name   # Specific test target
+cargo nextest run --release --workspace        # All crates
+cargo test --doc --release --workspace         # Doc tests
 ```
 
 - Private functions: `#[cfg(test)]` module in source file
 - Integration tests: `tests/` directory
+- Use `cargo nextest run` for unit and integration tests; keep doctests on `cargo test --doc`.
 - **Test tolerance changes**: When relaxing test tolerances (unit tests, codecov targets, etc.), always seek explicit user approval before making changes.
 - **Coverage-driven additions**: Meet the threshold with meaningful behavior-focused tests. Do not add filler tests solely to raise coverage numbers.
 
@@ -215,13 +217,14 @@ Before creating a PR, always run these checks locally:
 ```bash
 cargo fmt --all          # Format all code
 cargo clippy --workspace # Check for common issues
-cargo test --release --workspace   # Run all tests
+cargo nextest run --release --workspace --no-fail-fast   # Run unit and integration tests
+cargo test --doc --release --workspace                   # Run doc tests
 ```
 
 **Coverage check (must pass before push):**
 
 ```bash
-cargo llvm-cov --workspace --json --output-path coverage.json
+cargo llvm-cov nextest --workspace --release --json --output-path coverage.json
 python3 scripts/check-coverage.py coverage.json
 ```
 
diff --git a/README.md b/README.md
index 49348be..952ffdf 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@ Template repository for Rust workspace projects in the tensor4all organization.
 ## What's included
 
 - **Cargo workspace** — empty workspace ready to add crates
-- **CI (GitHub Actions)** — fmt, test (ubuntu + macOS), coverage, doc
+- **CI (GitHub Actions)** — fmt, nextest + doctest (ubuntu + macOS), coverage, doc
 - **Coverage checking** — per-file line coverage thresholds via `cargo llvm-cov`
 - **Agent guidelines** — CLAUDE.md / AGENTS.md for AI-assisted development
 
@@ -43,6 +43,15 @@ Artifacts:
 - durable reports: `docs/test-reports/agentic-bug-sweep/`
 - ephemeral execution state: `target/agentic-bug-sweep/`
 
+## Testing
+
+Run unit and integration tests with nextest, and keep doctests as a separate step:
+
+```bash
+cargo nextest run --workspace --release --no-fail-fast
+cargo test --doc --workspace --release
+```
+
 ## Coverage
 
 Coverage is checked per-file against thresholds in `coverage-thresholds.json`.
@@ -50,7 +59,7 @@ Meet the configured threshold with meaningful tests rather than filler assertion
 
 ```bash
 # Run locally
-cargo llvm-cov --workspace --json --output-path coverage.json
+cargo llvm-cov nextest --workspace --release --json --output-path coverage.json
 python3 scripts/check-coverage.py coverage.json
 ```
 
diff --git a/ai/common-agent-rules.md b/ai/common-agent-rules.md
index f26c63a..6a020f4 100644
--- a/ai/common-agent-rules.md
+++ b/ai/common-agent-rules.md
@@ -60,8 +60,8 @@ When in doubt, ask: *"Would an experienced software engineer consider this clean
 - When proceeding on NFS, place Cargo build artifacts on local disk rather than
   inside the repository checkout.
 - Prefer a stable repo-specific local target directory such as
-  `CARGO_TARGET_DIR=/tmp/<repo>-target` for `cargo build`, `cargo test`,
-  `cargo llvm-cov`, and similar heavy commands.
+  `CARGO_TARGET_DIR=/tmp/<repo>-target` for `cargo build`, `cargo nextest run`,
+  `cargo test --doc`, `cargo llvm-cov`, and similar heavy commands.
 
 ## File Organization
 
diff --git a/ai/new-tensor4all-rust-repo/scripts/new-repo.sh b/ai/new-tensor4all-rust-repo/scripts/new-repo.sh
index b8a76d8..af1a60b 100755
--- a/ai/new-tensor4all-rust-repo/scripts/new-repo.sh
+++ b/ai/new-tensor4all-rust-repo/scripts/new-repo.sh
@@ -188,7 +188,13 @@ ASSETS_SYNCED=1
 if ! run_in_repo cargo fmt --all --check; then
   fail_with_summary 1 "cargo fmt --all --check failed in $DEST_PATH"
 fi
-if ! run_in_repo cargo llvm-cov --workspace --release --json --output-path coverage.json; then
+if ! run_in_repo cargo nextest run --workspace --release --no-fail-fast; then
+  fail_with_summary 1 "cargo nextest run failed in $DEST_PATH"
+fi
+if ! run_in_repo cargo test --doc --workspace --release; then
+  fail_with_summary 1 "cargo test --doc failed in $DEST_PATH"
+fi
+if ! run_in_repo cargo llvm-cov nextest --workspace --release --json --output-path coverage.json; then
   fail_with_summary 1 "cargo llvm-cov failed in $DEST_PATH"
 fi
 if ! run_in_repo python3 scripts/check-coverage.py coverage.json; then
diff --git a/ai/numerical-rust-rules.md b/ai/numerical-rust-rules.md
index f324235..ff942a4 100644
--- a/ai/numerical-rust-rules.md
+++ b/ai/numerical-rust-rules.md
@@ -8,7 +8,8 @@ are illustrative — apply the same reasoning to any new pattern.
 - Use small deterministic inputs for correctness tests.
 - Prefer hard-coded data or seeded RNGs over unseeded randomness.
 - Feature-gate expensive tests.
-- For local trial-and-error loops, `cargo test --release --workspace` is preferred when it materially reduces iteration time.
+- For local trial-and-error loops, prefer `cargo nextest run --release --workspace --no-fail-fast` for unit and integration tests.
+- Run doctests separately with `cargo test --doc --release --workspace`; `nextest` does not replace them.
 
 ## Generic Test Patterns
 
diff --git a/ai/pr-workflow-rules.md b/ai/pr-workflow-rules.md
index ae0db73..e06cf71 100644
--- a/ai/pr-workflow-rules.md
+++ b/ai/pr-workflow-rules.md
@@ -16,13 +16,16 @@ Before pushing or creating a PR, all of these must pass:
 
 ```bash
 cargo fmt --all --check
-cargo llvm-cov --workspace --release --json --output-path coverage.json
+cargo nextest run --workspace --release --no-fail-fast
+cargo test --doc --workspace --release
+cargo llvm-cov nextest --workspace --release --json --output-path coverage.json
 python3 scripts/check-coverage.py coverage.json
 cargo doc --workspace --no-deps
 python3 scripts/check-docs-site.py
 ```
 
 If formatting fails, run `cargo fmt --all` and rerun the checks.
+Keep doctests as a dedicated `cargo test --doc` step; `cargo nextest` does not execute them.
 
 ## Repository Settings
 
diff --git a/ai/repo-settings.json b/ai/repo-settings.json
index 6b83fde..7b1cdcc 100644
--- a/ai/repo-settings.json
+++ b/ai/repo-settings.json
@@ -6,8 +6,8 @@
     "strict": true,
     "contexts": [
       "rustfmt",
-      "cargo test (ubuntu-latest)",
-      "cargo test (macos-latest)",
+      "nextest (ubuntu-latest)",
+      "nextest (macos-latest)",
       "coverage",
       "docs-site"
     ]
diff --git a/docs/plans/2026-03-11-nextest-rollout-implementation.md b/docs/plans/2026-03-11-nextest-rollout-implementation.md
new file mode 100644
index 0000000..39b18df
--- /dev/null
+++ b/docs/plans/2026-03-11-nextest-rollout-implementation.md
@@ -0,0 +1,124 @@
+# Nextest Rollout Implementation Plan
+
+> **For Claude:** REQUIRED SUB-SKILL: Use superpowers:executing-plans to implement this plan task-by-task.
+
+**Goal:** Make `cargo nextest` the default test runner across the template's CI, repository settings, helper scripts, and coding rules while keeping doctests explicitly covered.
+
+**Architecture:** Add a small regression test that validates the template's expected verification commands and required status-check names from repository files. Then update the workflow, settings, helper scripts, and rule documents together so the repository describes and executes one consistent testing strategy: `cargo nextest run` for normal tests, `cargo test --doc` for doctests, and `cargo llvm-cov nextest` for coverage.
+
+**Tech Stack:** GitHub Actions YAML, Bash scripts, JSON, Markdown, Python `unittest`
+
+---
+
+### Task 1: Add regression coverage for the rollout
+
+**Files:**
+- Create: `scripts/tests/test_nextest_rollout.py`
+
+**Step 1: Write the failing test**
+
+Add a Python `unittest` module that reads repository files as text and asserts:
+- `.github/workflows/ci.yml` contains a `nextest`-named test job, installs `cargo-nextest`, runs `cargo nextest run --workspace --release --no-fail-fast`, and runs `cargo test --doc --workspace --release`
+- `ai/repo-settings.json` uses `nextest (ubuntu-latest)` and `nextest (macos-latest)` as required status checks
+- `scripts/create-pr.sh` and `ai/new-tensor4all-rust-repo/scripts/new-repo.sh` mention the `nextest`/doctest verification commands
+
+**Step 2: Run test to verify it fails**
+
+Run: `python3 -m unittest scripts.tests.test_nextest_rollout -v`
+Expected: FAIL because the repository still references `cargo test` rather than `nextest`
+
+**Step 3: Commit**
+
+Do not commit yet; continue once the test is red.
+
+### Task 2: Update execution paths to use nextest
+
+**Files:**
+- Modify: `.github/workflows/ci.yml`
+- Modify: `ai/repo-settings.json`
+- Modify: `scripts/create-pr.sh`
+- Modify: `ai/new-tensor4all-rust-repo/scripts/new-repo.sh`
+
+**Step 1: Write minimal implementation**
+
+Update CI and helper scripts so they all use the same command set:
+- install `cargo-nextest` where needed
+- use `cargo nextest run --workspace --release --no-fail-fast` for standard test execution
+- run `cargo test --doc --workspace --release` explicitly for doctests
+- use `cargo llvm-cov nextest --workspace --release --json --output-path coverage.json` for coverage
+- rename required status-check contexts to match the workflow job names
+
+**Step 2: Run targeted regression test**
+
+Run: `python3 -m unittest scripts.tests.test_nextest_rollout -v`
+Expected: PASS
+
+**Step 3: Run command-level verification**
+
+Run:
+- `cargo nextest run --workspace --release --no-fail-fast`
+- `cargo test --doc --workspace --release`
+- `cargo llvm-cov nextest --workspace --release --json --output-path coverage.json`
+- `python3 scripts/check-coverage.py coverage.json`
+
+Expected: all commands exit successfully
+
+### Task 3: Update rule and template documentation
+
+**Files:**
+- Modify: `AGENTS.md`
+- Modify: `README.md`
+- Modify: `ai/numerical-rust-rules.md`
+- Modify: `ai/pr-workflow-rules.md`
+
+**Step 1: Write minimal implementation**
+
+Replace `cargo test` examples with `cargo nextest run` where the guidance is about standard unit/integration test execution, and add an explicit note that doctests remain a separate `cargo test --doc` step.
+
+**Step 2: Re-run the regression test**
+
+Run: `python3 -m unittest scripts.tests.test_nextest_rollout -v`
+Expected: PASS
+
+**Step 3: Run full local verification**
+
+Run:
+- `cargo fmt --all`
+- `cargo fmt --all --check`
+- `cargo clippy --workspace`
+- `python3 -m unittest scripts.tests.test_nextest_rollout -v`
+- `cargo nextest run --workspace --release --no-fail-fast`
+- `cargo test --doc --workspace --release`
+- `cargo llvm-cov nextest --workspace --release --json --output-path coverage.json`
+- `python3 scripts/check-coverage.py coverage.json`
+- `cargo doc --workspace --no-deps`
+- `python3 scripts/check-docs-site.py`
+
+Expected: all commands pass
+
+### Task 4: Commit, push, create PR, and enable auto-merge
+
+**Files:**
+- Modify: PR body generated from `scripts/create-pr.sh` or pass explicit body via `gh pr create`
+
+**Step 1: Commit**
+
+Run:
+```bash
+git add .github/workflows/ci.yml ai/repo-settings.json scripts/create-pr.sh ai/new-tensor4all-rust-repo/scripts/new-repo.sh AGENTS.md README.md ai/numerical-rust-rules.md ai/pr-workflow-rules.md scripts/tests/test_nextest_rollout.py docs/plans/2026-03-11-nextest-rollout-implementation.md
+git commit -m "ci: adopt nextest across template workflows"
+```
+
+**Step 2: Push and create PR**
+
+Run:
+```bash
+git push -u origin rules/nextest-template
+gh pr create --base main --title "ci: adopt nextest across template workflows" --body-file <prepared-body>
+gh pr merge --auto --squash --delete-branch
+```
+
+**Step 3: Monitor CI**
+
+Run: `bash scripts/monitor-pr-checks.sh <pr-url-or-number> --interval 30`
+Expected: all required checks pass; auto-merge completes
diff --git a/scripts/create-pr.sh b/scripts/create-pr.sh
index c8c6ec8..381b299 100755
--- a/scripts/create-pr.sh
+++ b/scripts/create-pr.sh
@@ -50,7 +50,9 @@ ensure_body_file() {
     git log --format='- %s' "${BASE_BRANCH}..HEAD" 2>/dev/null || true
     printf '\n## Verification\n\n'
     printf -- '- `cargo fmt --all --check`\n'
-    printf -- '- `cargo llvm-cov --workspace --release --json --output-path coverage.json`\n'
+    printf -- '- `cargo nextest run --workspace --release --no-fail-fast`\n'
+    printf -- '- `cargo test --doc --workspace --release`\n'
+    printf -- '- `cargo llvm-cov nextest --workspace --release --json --output-path coverage.json`\n'
     printf -- '- `python3 scripts/check-coverage.py coverage.json`\n'
     printf -- '- `cargo doc --workspace --no-deps`\n'
     printf -- '- `python3 scripts/check-docs-site.py`\n'
@@ -73,7 +75,9 @@ append_ai_attribution() {
 
 run_required_checks() {
   cargo fmt --all --check
-  cargo llvm-cov --workspace --release --json --output-path coverage.json
+  cargo nextest run --workspace --release --no-fail-fast
+  cargo test --doc --workspace --release
+  cargo llvm-cov nextest --workspace --release --json --output-path coverage.json
   python3 scripts/check-coverage.py coverage.json
   cargo doc --workspace --no-deps
   python3 scripts/check-docs-site.py
diff --git a/scripts/tests/test_nextest_rollout.py b/scripts/tests/test_nextest_rollout.py
new file mode 100644
index 0000000..9ab6a30
--- /dev/null
+++ b/scripts/tests/test_nextest_rollout.py
@@ -0,0 +1,71 @@
+import json
+import unittest
+from pathlib import Path
+
+
+REPO_ROOT = Path(__file__).resolve().parents[2]
+
+
+def read_text(path: str) -> str:
+    return (REPO_ROOT / path).read_text(encoding="utf-8")
+
+
+class NextestRolloutTests(unittest.TestCase):
+    def test_ci_uses_nextest_and_explicit_doctests(self) -> None:
+        workflow = read_text(".github/workflows/ci.yml")
+
+        self.assertIn("name: nextest (${{ matrix.os }})", workflow)
+        self.assertIn("taiki-e/install-action@nextest", workflow)
+        self.assertIn(
+            "cargo nextest run --workspace --release --no-fail-fast",
+            workflow,
+        )
+        self.assertIn("cargo test --doc --workspace --release", workflow)
+        self.assertIn(
+            "cargo llvm-cov nextest --workspace --release --json --output-path coverage.json",
+            workflow,
+        )
+
+    def test_repo_settings_match_nextest_job_names(self) -> None:
+        settings = json.loads(read_text("ai/repo-settings.json"))
+
+        self.assertEqual(
+            settings["required_status_checks"]["contexts"],
+            [
+                "rustfmt",
+                "nextest (ubuntu-latest)",
+                "nextest (macos-latest)",
+                "coverage",
+                "docs-site",
+            ],
+        )
+
+    def test_helper_scripts_use_nextest_verification_commands(self) -> None:
+        create_pr = read_text("scripts/create-pr.sh")
+        bootstrap = read_text("ai/new-tensor4all-rust-repo/scripts/new-repo.sh")
+
+        for content in (create_pr, bootstrap):
+            self.assertIn(
+                "cargo nextest run --workspace --release --no-fail-fast",
+                content,
+            )
+            self.assertIn("cargo test --doc --workspace --release", content)
+            self.assertIn(
+                "cargo llvm-cov nextest --workspace --release --json --output-path coverage.json",
+                content,
+            )
+
+    def test_docs_and_rules_prefer_nextest_with_explicit_doctests(self) -> None:
+        for path in (
+            "README.md",
+            "AGENTS.md",
+            "ai/numerical-rust-rules.md",
+            "ai/pr-workflow-rules.md",
+        ):
+            content = read_text(path)
+            self.assertIn("cargo nextest", content, msg=f"missing nextest in {path}")
+            self.assertIn("cargo test --doc", content, msg=f"missing doctest guidance in {path}")
+
+
+if __name__ == "__main__":
+    unittest.main()