feat(dev-fkeys): add project-aware F4 compile/run dispatcher

I added a new module `modules/dev-fkeys.el` that owns the dev F-key block. F4 prompts via `completing-read` with a candidate set filtered by project type (compiled / interpreted / unknown). C-F4 is the compile-only fast path. M-F4 is clean + rebuild. It runs a heuristic clean command derived from the project markers (go.mod, Cargo.toml, Eask, Makefile, CMakeLists.txt) and chains `projectile-compile-project` on success. S-F4 stays on `recompile` and now lives globally instead of duplicated across prog-general.el and prog-c.el. F6 is bound globally to `projectile-test-project` as a Phase 1 stopgap. Phase 2 replaces it with the polyglot test runner spec'd in todo.org.

Project-type detection runs against the projectile root and falls back to `unknown` when no marker matches. Interpreted markers are checked first so a Python or Node project with a Makefile for tasks classifies as interpreted instead of compiled. Compile + Run sequencing uses a one-shot `compilation-finish-functions` hook that self-removes on first invocation and only fires the follow-up when the status string starts with `finished`.

Cleanup in the same commit:
- Dropped F4/F5/F6 from `prog-general.el`'s prog-mode-hook. They are now global.
- Dropped F6→format bindings from prog-c.el / prog-python.el / prog-shell.el. C-; f was already bound in each, so this is pure removal.
- Dropped the duplicate S-F4 from prog-c.el. The global binding covers it.
- Updated the keybinding header in prog-general.el and the workflow comments in prog-c.el / prog-shell.el.
- Wired `(require 'dev-fkeys)` in init.el alongside coverage-core.

TDD: 73 tests across 11 files, one per helper. Production code is split into small testable internals (`cj/--detect-project-type`, `cj/--f4-candidates`, `cj/--f4-derive-clean-cmd`, `cj/--f4-make-once-hook`, `cj/--f4-dispatch`, `cj/--f4-compile-and-run-impl`, `cj/--f4-clean-rebuild-impl`, `cj/--f4-project-root`) plus three thin interactive wrappers. Smoke tests confirm bindings register on load.

Known limitation: if another `compilation-finish-functions` hook fires between my add-hook and the compile finishing, the chain can fire on the wrong compile. The hook self-removes on first invocation regardless of which compile it sees. Documented in the impl docstring. Acceptable for v1.

Phase 2 will replace F6 with the polyglot test runner (tree-sitter queries for Python/Go/TS, sexp scan for Elisp, buffer-local last-test memory).

11 files changed, 929 insertions, 0 deletions

diff --git a/tests/test-dev-fkeys--detect-project-type.el b/tests/test-dev-fkeys--detect-project-type.el
new file mode 100644
index 00000000..3b306484
--- /dev/null
+++ b/tests/test-dev-fkeys--detect-project-type.el
@@ -0,0 +1,117 @@
+;;; test-dev-fkeys--detect-project-type.el --- Tests for cj/--detect-project-type -*- lexical-binding: t -*-
+
+;;; Commentary:
+;; Tests for the project-type classifier in dev-fkeys.el.
+;; The classifier returns 'compiled, 'interpreted, or 'unknown based on
+;; marker files at the project root. Interpreted markers are checked first
+;; so a Python or Node project with a Makefile for tasks classifies as
+;; interpreted.
+
+;;; Code:
+
+(require 'ert)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'dev-fkeys)
+
+(defmacro test-dev-fkeys--with-project-dir (markers &rest body)
+  "Create a temp project dir with each filename in MARKERS as an empty file.
+Bind the dir path to ROOT in BODY. Cleans up on exit."
+  (declare (indent 1))
+  `(let ((root (make-temp-file "test-dev-fkeys-" t)))
+     (unwind-protect
+         (progn
+           (dolist (marker ,markers)
+             (write-region "" nil (expand-file-name marker root)))
+           ,@body)
+       (delete-directory root t))))
+
+;;; Normal Cases
+
+(ert-deftest test-dev-fkeys-detect-project-type-go-mod-is-compiled ()
+  "Normal: go.mod marker classifies as compiled."
+  (test-dev-fkeys--with-project-dir '("go.mod")
+    (should (eq (cj/--detect-project-type root) 'compiled))))
+
+(ert-deftest test-dev-fkeys-detect-project-type-cargo-toml-is-compiled ()
+  "Normal: Cargo.toml marker classifies as compiled."
+  (test-dev-fkeys--with-project-dir '("Cargo.toml")
+    (should (eq (cj/--detect-project-type root) 'compiled))))
+
+(ert-deftest test-dev-fkeys-detect-project-type-cmakelists-is-compiled ()
+  "Normal: CMakeLists.txt marker classifies as compiled."
+  (test-dev-fkeys--with-project-dir '("CMakeLists.txt")
+    (should (eq (cj/--detect-project-type root) 'compiled))))
+
+(ert-deftest test-dev-fkeys-detect-project-type-makefile-is-compiled ()
+  "Normal: Makefile marker classifies as compiled."
+  (test-dev-fkeys--with-project-dir '("Makefile")
+    (should (eq (cj/--detect-project-type root) 'compiled))))
+
+(ert-deftest test-dev-fkeys-detect-project-type-eask-is-compiled ()
+  "Normal: Eask marker classifies as compiled."
+  (test-dev-fkeys--with-project-dir '("Eask")
+    (should (eq (cj/--detect-project-type root) 'compiled))))
+
+(ert-deftest test-dev-fkeys-detect-project-type-pyproject-is-interpreted ()
+  "Normal: pyproject.toml marker classifies as interpreted."
+  (test-dev-fkeys--with-project-dir '("pyproject.toml")
+    (should (eq (cj/--detect-project-type root) 'interpreted))))
+
+(ert-deftest test-dev-fkeys-detect-project-type-requirements-is-interpreted ()
+  "Normal: requirements.txt marker classifies as interpreted."
+  (test-dev-fkeys--with-project-dir '("requirements.txt")
+    (should (eq (cj/--detect-project-type root) 'interpreted))))
+
+(ert-deftest test-dev-fkeys-detect-project-type-pipfile-is-interpreted ()
+  "Normal: Pipfile marker classifies as interpreted."
+  (test-dev-fkeys--with-project-dir '("Pipfile")
+    (should (eq (cj/--detect-project-type root) 'interpreted))))
+
+(ert-deftest test-dev-fkeys-detect-project-type-package-json-is-interpreted ()
+  "Normal: package.json marker classifies as interpreted."
+  (test-dev-fkeys--with-project-dir '("package.json")
+    (should (eq (cj/--detect-project-type root) 'interpreted))))
+
+;;; Boundary Cases
+
+(ert-deftest test-dev-fkeys-detect-project-type-interpreted-wins-over-compiled ()
+  "Boundary: a Python project with a Makefile classifies as interpreted.
+Interpreted markers are checked first so task-runner Makefiles in
+Python/Node projects don't misclassify them as compiled."
+  (test-dev-fkeys--with-project-dir '("pyproject.toml" "Makefile")
+    (should (eq (cj/--detect-project-type root) 'interpreted))))
+
+(ert-deftest test-dev-fkeys-detect-project-type-package-json-wins-over-makefile ()
+  "Boundary: package.json + Makefile classifies as interpreted."
+  (test-dev-fkeys--with-project-dir '("package.json" "Makefile")
+    (should (eq (cj/--detect-project-type root) 'interpreted))))
+
+(ert-deftest test-dev-fkeys-detect-project-type-pure-c-with-makefile-is-compiled ()
+  "Boundary: a Makefile alone (no interpreted markers) classifies as compiled.
+This is the typical pure-C project case."
+  (test-dev-fkeys--with-project-dir '("Makefile")
+    (should (eq (cj/--detect-project-type root) 'compiled))))
+
+(ert-deftest test-dev-fkeys-detect-project-type-no-markers-is-unknown ()
+  "Boundary: directory with no markers classifies as unknown."
+  (test-dev-fkeys--with-project-dir '()
+    (should (eq (cj/--detect-project-type root) 'unknown))))
+
+(ert-deftest test-dev-fkeys-detect-project-type-irrelevant-file-is-unknown ()
+  "Boundary: unrelated files in root don't trigger any classification."
+  (test-dev-fkeys--with-project-dir '("README.md" "LICENSE" ".gitignore")
+    (should (eq (cj/--detect-project-type root) 'unknown))))
+
+;;; Error Cases
+
+(ert-deftest test-dev-fkeys-detect-project-type-nil-root-is-unknown ()
+  "Error: nil ROOT returns 'unknown (buffer not in a project)."
+  (should (eq (cj/--detect-project-type nil) 'unknown)))
+
+(ert-deftest test-dev-fkeys-detect-project-type-nonexistent-root-is-unknown ()
+  "Error: a directory path that doesn't exist returns 'unknown.
+file-exists-p on a non-existent path returns nil, so no marker matches."
+  (should (eq (cj/--detect-project-type "/nonexistent/path/xyzzy") 'unknown)))
+
+(provide 'test-dev-fkeys--detect-project-type)
+;;; test-dev-fkeys--detect-project-type.el ends here
diff --git a/tests/test-dev-fkeys--f4-candidates.el b/tests/test-dev-fkeys--f4-candidates.el
new file mode 100644
index 00000000..a2d1afa4
--- /dev/null
+++ b/tests/test-dev-fkeys--f4-candidates.el
@@ -0,0 +1,66 @@
+;;; test-dev-fkeys--f4-candidates.el --- Tests for cj/--f4-candidates -*- lexical-binding: t -*-
+
+;;; Commentary:
+;; Tests for the candidate-menu builder. Returns an alist of
+;; (LABEL . ACTION) for the F4 completing-read prompt. The first entry
+;; is the default (selected on RET).
+
+;;; Code:
+
+(require 'ert)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'dev-fkeys)
+
+;;; Normal Cases
+
+(ert-deftest test-dev-fkeys-f4-candidates-compiled-has-four-entries ()
+  "Normal: compiled project gets all four candidates."
+  (let ((cands (cj/--f4-candidates 'compiled)))
+    (should (= (length cands) 4))))
+
+(ert-deftest test-dev-fkeys-f4-candidates-compiled-default-is-compile-and-run ()
+  "Normal: first candidate for compiled is Compile + Run (the default)."
+  (let ((cands (cj/--f4-candidates 'compiled)))
+    (should (equal (caar cands) "Compile + Run"))
+    (should (eq (cdar cands) 'compile-and-run))))
+
+(ert-deftest test-dev-fkeys-f4-candidates-compiled-includes-all-actions ()
+  "Normal: compiled menu maps each label to its action symbol."
+  (let ((cands (cj/--f4-candidates 'compiled)))
+    (should (eq (cdr (assoc "Compile + Run" cands))   'compile-and-run))
+    (should (eq (cdr (assoc "Compile" cands))         'compile-only))
+    (should (eq (cdr (assoc "Run" cands))             'run-only))
+    (should (eq (cdr (assoc "Clean + Rebuild" cands)) 'clean-rebuild))))
+
+(ert-deftest test-dev-fkeys-f4-candidates-interpreted-is-run-only ()
+  "Normal: interpreted project gets a single Run candidate."
+  (let ((cands (cj/--f4-candidates 'interpreted)))
+    (should (= (length cands) 1))
+    (should (equal (caar cands) "Run"))
+    (should (eq (cdar cands) 'run-only))))
+
+(ert-deftest test-dev-fkeys-f4-candidates-unknown-is-compile-plain ()
+  "Normal: unknown project gets a single Compile candidate that calls plain compile."
+  (let ((cands (cj/--f4-candidates 'unknown)))
+    (should (= (length cands) 1))
+    (should (equal (caar cands) "Compile"))
+    (should (eq (cdar cands) 'compile-plain))))
+
+;;; Boundary Cases
+
+(ert-deftest test-dev-fkeys-f4-candidates-bogus-symbol-falls-back-to-unknown ()
+  "Boundary: an unrecognized project-type symbol falls through to the unknown branch."
+  (let ((cands (cj/--f4-candidates 'fictional-type)))
+    (should (= (length cands) 1))
+    (should (eq (cdar cands) 'compile-plain))))
+
+;;; Error Cases
+
+(ert-deftest test-dev-fkeys-f4-candidates-nil-falls-back-to-unknown ()
+  "Error: nil project-type falls through to the unknown branch."
+  (let ((cands (cj/--f4-candidates nil)))
+    (should (= (length cands) 1))
+    (should (eq (cdar cands) 'compile-plain))))
+
+(provide 'test-dev-fkeys--f4-candidates)
+;;; test-dev-fkeys--f4-candidates.el ends here
diff --git a/tests/test-dev-fkeys--f4-clean-rebuild-impl.el b/tests/test-dev-fkeys--f4-clean-rebuild-impl.el
new file mode 100644
index 00000000..27c7c56a
--- /dev/null
+++ b/tests/test-dev-fkeys--f4-clean-rebuild-impl.el
@@ -0,0 +1,118 @@
+;;; test-dev-fkeys--f4-clean-rebuild-impl.el --- Tests for cj/--f4-clean-rebuild-impl -*- lexical-binding: t -*-
+
+;;; Commentary:
+;; Tests for the "Clean + Rebuild" action handler. Runs the heuristic clean
+;; command via `compile' from the project root, then chains
+;; `projectile-compile-project' on success via the one-shot finish hook.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'dev-fkeys)
+
+(defmacro test-dev-fkeys-cr--with-project (markers &rest body)
+  "Create a temp project dir with each filename in MARKERS as an empty file.
+Bind the dir path to ROOT in BODY. Cleans up on exit."
+  (declare (indent 1))
+  `(let ((root (make-temp-file "test-dev-fkeys-cr-" t)))
+     (unwind-protect
+         (progn
+           (dolist (marker ,markers)
+             (write-region "" nil (expand-file-name marker root)))
+           ,@body)
+       (delete-directory root t))))
+
+;;; Normal Cases
+
+(ert-deftest test-dev-fkeys-clean-rebuild-impl-runs-derived-clean-cmd ()
+  "Normal: handler invokes `compile' with the heuristic clean command for the
+project marker present at ROOT.
+
+Components integrated:
+- `cj/--f4-clean-rebuild-impl' (unit under test)
+- `cj/--f4-derive-clean-cmd' (real)
+- `compile' (MOCKED — captures the command string)
+- `projectile-compile-project' (MOCKED — no-op)
+- `compilation-finish-functions' (real, scoped via let)"
+  (test-dev-fkeys-cr--with-project '("Makefile")
+    (let ((compile-calls nil)
+          (compilation-finish-functions nil))
+      (cl-letf (((symbol-function 'compile)
+                 (lambda (cmd) (push cmd compile-calls)))
+                ((symbol-function 'projectile-compile-project)
+                 (lambda (_arg) nil)))
+        (cj/--f4-clean-rebuild-impl root)
+        (should (equal compile-calls '("make clean")))))))
+
+(ert-deftest test-dev-fkeys-clean-rebuild-impl-installs-finish-hook ()
+  "Normal: handler installs exactly one hook in `compilation-finish-functions'."
+  (test-dev-fkeys-cr--with-project '("go.mod")
+    (let ((compilation-finish-functions nil))
+      (cl-letf (((symbol-function 'compile) (lambda (_cmd) nil))
+                ((symbol-function 'projectile-compile-project)
+                 (lambda (_arg) nil)))
+        (cj/--f4-clean-rebuild-impl root)
+        (should (= (length compilation-finish-functions) 1))))))
+
+(ert-deftest test-dev-fkeys-clean-rebuild-impl-hook-runs-projectile-compile-on-success ()
+  "Normal: when the clean step finishes successfully, the installed hook
+calls `projectile-compile-project' to do the rebuild."
+  (test-dev-fkeys-cr--with-project '("Cargo.toml")
+    (let ((compile-calls 0)
+          (compilation-finish-functions nil))
+      (cl-letf (((symbol-function 'compile) (lambda (_cmd) nil))
+                ((symbol-function 'projectile-compile-project)
+                 (lambda (_arg) (cl-incf compile-calls))))
+        (cj/--f4-clean-rebuild-impl root)
+        (run-hook-with-args 'compilation-finish-functions nil "finished\n")
+        (should (= compile-calls 1))))))
+
+(ert-deftest test-dev-fkeys-clean-rebuild-impl-runs-clean-from-project-root ()
+  "Normal: the clean compile runs with default-directory bound to ROOT."
+  (test-dev-fkeys-cr--with-project '("Eask")
+    (let ((seen-dir nil)
+          (compilation-finish-functions nil))
+      (cl-letf (((symbol-function 'compile)
+                 (lambda (_cmd) (setq seen-dir default-directory)))
+                ((symbol-function 'projectile-compile-project)
+                 (lambda (_arg) nil)))
+        (cj/--f4-clean-rebuild-impl root)
+        (should (string= (file-name-as-directory seen-dir)
+                         (file-name-as-directory root)))))))
+
+;;; Boundary Cases
+
+(ert-deftest test-dev-fkeys-clean-rebuild-impl-hook-skips-rebuild-on-failure ()
+  "Boundary: when the clean step fails, projectile-compile-project does not run."
+  (test-dev-fkeys-cr--with-project '("Makefile")
+    (let ((compile-calls 0)
+          (compilation-finish-functions nil))
+      (cl-letf (((symbol-function 'compile) (lambda (_cmd) nil))
+                ((symbol-function 'projectile-compile-project)
+                 (lambda (_arg) (cl-incf compile-calls))))
+        (cj/--f4-clean-rebuild-impl root)
+        (run-hook-with-args 'compilation-finish-functions nil "exited abnormally\n")
+        (should (= compile-calls 0))))))
+
+;;; Error Cases
+
+(ert-deftest test-dev-fkeys-clean-rebuild-impl-no-clean-cmd-signals-user-error ()
+  "Error: a project root with no recognized markers signals a user-error
+rather than silently running nothing."
+  (test-dev-fkeys-cr--with-project '("README.md")
+    (cl-letf (((symbol-function 'compile) (lambda (_cmd) nil))
+              ((symbol-function 'projectile-compile-project)
+               (lambda (_arg) nil)))
+      (should-error (cj/--f4-clean-rebuild-impl root) :type 'user-error))))
+
+(ert-deftest test-dev-fkeys-clean-rebuild-impl-nil-root-signals-user-error ()
+  "Error: a nil root signals a user-error (no project detected)."
+  (cl-letf (((symbol-function 'compile) (lambda (_cmd) nil))
+            ((symbol-function 'projectile-compile-project)
+             (lambda (_arg) nil)))
+    (should-error (cj/--f4-clean-rebuild-impl nil) :type 'user-error)))
+
+(provide 'test-dev-fkeys--f4-clean-rebuild-impl)
+;;; test-dev-fkeys--f4-clean-rebuild-impl.el ends here
diff --git a/tests/test-dev-fkeys--f4-clean-rebuild.el b/tests/test-dev-fkeys--f4-clean-rebuild.el
new file mode 100644
index 00000000..040ce930
--- /dev/null
+++ b/tests/test-dev-fkeys--f4-clean-rebuild.el
@@ -0,0 +1,61 @@
+;;; test-dev-fkeys--f4-clean-rebuild.el --- Smoke tests for cj/f4-clean-rebuild -*- lexical-binding: t -*-
+
+;;; Commentary:
+;; Smoke tests for the M-F4 fast path. On a compiled project, runs the
+;; clean-rebuild handler. Interpreted and unknown projects get a no-op
+;; message — no rebuild attempt, no error.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'dev-fkeys)
+
+(defmacro test-dev-fkeys-cr-w--with-project (markers &rest body)
+  "Set up a temp project with MARKERS, bind ROOT, run BODY, clean up."
+  (declare (indent 1))
+  `(let ((root (make-temp-file "test-dev-fkeys-cr-w-" t)))
+     (unwind-protect
+         (progn
+           (dolist (marker ,markers)
+             (write-region "" nil (expand-file-name marker root)))
+           ,@body)
+       (delete-directory root t))))
+
+;;; Normal Cases
+
+(ert-deftest test-dev-fkeys-f4-clean-rebuild-compiled-project-runs-impl-with-root ()
+  "Normal: on a compiled project, calls cj/--f4-clean-rebuild-impl with the
+project root."
+  (test-dev-fkeys-cr-w--with-project '("Makefile")
+    (let (received-root)
+      (cl-letf (((symbol-function 'cj/--f4-project-root) (lambda () root))
+                ((symbol-function 'cj/--f4-clean-rebuild-impl)
+                 (lambda (r) (setq received-root r))))
+        (cj/f4-clean-rebuild)
+        (should (string= received-root root))))))
+
+(ert-deftest test-dev-fkeys-f4-clean-rebuild-interpreted-project-skips-impl ()
+  "Normal: on an interpreted project, the impl handler is not invoked."
+  (test-dev-fkeys-cr-w--with-project '("pyproject.toml")
+    (let ((calls 0))
+      (cl-letf (((symbol-function 'cj/--f4-project-root) (lambda () root))
+                ((symbol-function 'cj/--f4-clean-rebuild-impl)
+                 (lambda (_r) (cl-incf calls))))
+        (cj/f4-clean-rebuild)
+        (should (= calls 0))))))
+
+;;; Boundary Cases
+
+(ert-deftest test-dev-fkeys-f4-clean-rebuild-unknown-project-skips-impl ()
+  "Boundary: outside any project, the impl handler is not invoked."
+  (let ((calls 0))
+    (cl-letf (((symbol-function 'cj/--f4-project-root) (lambda () nil))
+              ((symbol-function 'cj/--f4-clean-rebuild-impl)
+               (lambda (_r) (cl-incf calls))))
+      (cj/f4-clean-rebuild)
+      (should (= calls 0)))))
+
+(provide 'test-dev-fkeys--f4-clean-rebuild)
+;;; test-dev-fkeys--f4-clean-rebuild.el ends here
diff --git a/tests/test-dev-fkeys--f4-compile-and-run-impl.el b/tests/test-dev-fkeys--f4-compile-and-run-impl.el
new file mode 100644
index 00000000..d59a6cd6
--- /dev/null
+++ b/tests/test-dev-fkeys--f4-compile-and-run-impl.el
@@ -0,0 +1,75 @@
+;;; test-dev-fkeys--f4-compile-and-run-impl.el --- Tests for cj/--f4-compile-and-run-impl -*- lexical-binding: t -*-
+
+;;; Commentary:
+;; Tests for the "Compile + Run" action handler. After kicking off the
+;; compile, attaches a one-shot `compilation-finish-functions' hook that
+;; runs the project on success.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'dev-fkeys)
+
+;;; Normal Cases
+
+(ert-deftest test-dev-fkeys-compile-and-run-impl-invokes-projectile-compile ()
+  "Normal: handler calls `projectile-compile-project'.
+
+Components integrated:
+- `cj/--f4-compile-and-run-impl' (unit under test)
+- `projectile-compile-project' (MOCKED via cl-letf)
+- `compilation-finish-functions' (real, scoped via let)"
+  (let ((compile-calls 0)
+        (compilation-finish-functions nil))
+    (cl-letf (((symbol-function 'projectile-compile-project)
+               (lambda (_arg) (cl-incf compile-calls))))
+      (cj/--f4-compile-and-run-impl)
+      (should (= compile-calls 1)))))
+
+(ert-deftest test-dev-fkeys-compile-and-run-impl-installs-finish-hook ()
+  "Normal: handler installs exactly one hook in `compilation-finish-functions'."
+  (let ((compilation-finish-functions nil))
+    (cl-letf (((symbol-function 'projectile-compile-project)
+               (lambda (_arg) nil)))
+      (cj/--f4-compile-and-run-impl)
+      (should (= (length compilation-finish-functions) 1)))))
+
+(ert-deftest test-dev-fkeys-compile-and-run-impl-hook-runs-projectile-run-on-success ()
+  "Normal: when the compile finishes successfully, the installed hook calls
+`projectile-run-project'.
+
+Components integrated:
+- `cj/--f4-compile-and-run-impl' (unit under test)
+- `projectile-compile-project' (MOCKED — no-op)
+- `projectile-run-project' (MOCKED — counts calls)
+- `compilation-finish-functions' (real)
+- `run-hook-with-args' (real — simulates compile.el firing the hook)"
+  (let ((run-calls 0)
+        (compilation-finish-functions nil))
+    (cl-letf (((symbol-function 'projectile-compile-project)
+               (lambda (_arg) nil))
+              ((symbol-function 'projectile-run-project)
+               (lambda (_arg) (cl-incf run-calls))))
+      (cj/--f4-compile-and-run-impl)
+      (run-hook-with-args 'compilation-finish-functions nil "finished\n")
+      (should (= run-calls 1)))))
+
+;;; Boundary Cases
+
+(ert-deftest test-dev-fkeys-compile-and-run-impl-hook-skips-projectile-run-on-failure ()
+  "Boundary: when the compile fails, projectile-run-project must not run.
+The hook still self-removes (covered in the make-once-hook tests)."
+  (let ((run-calls 0)
+        (compilation-finish-functions nil))
+    (cl-letf (((symbol-function 'projectile-compile-project)
+               (lambda (_arg) nil))
+              ((symbol-function 'projectile-run-project)
+               (lambda (_arg) (cl-incf run-calls))))
+      (cj/--f4-compile-and-run-impl)
+      (run-hook-with-args 'compilation-finish-functions nil "exited abnormally\n")
+      (should (= run-calls 0)))))
+
+(provide 'test-dev-fkeys--f4-compile-and-run-impl)
+;;; test-dev-fkeys--f4-compile-and-run-impl.el ends here
diff --git a/tests/test-dev-fkeys--f4-compile-and-run.el b/tests/test-dev-fkeys--f4-compile-and-run.el
new file mode 100644
index 00000000..3e0da877
--- /dev/null
+++ b/tests/test-dev-fkeys--f4-compile-and-run.el
@@ -0,0 +1,94 @@
+;;; test-dev-fkeys--f4-compile-and-run.el --- Smoke tests for cj/f4-compile-and-run -*- lexical-binding: t -*-
+
+;;; Commentary:
+;; Smoke tests for the interactive F4 wrapper. The wrapper:
+;;
+;; 1. Resolves the project root.
+;; 2. Detects project type from markers.
+;; 3. Builds the candidate list.
+;; 4. Prompts via completing-read.
+;; 5. Looks up the chosen label's action.
+;; 6. Dispatches.
+;;
+;; Per the elisp-testing rule on Interactive vs Internal split, the heavy
+;; lifting is in `cj/--f4-dispatch' and the helpers — those are tested
+;; directly in their own files. This file just confirms the wrapper wires
+;; the pieces together: prompt fires, the chosen label routes to the right
+;; action symbol.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'dev-fkeys)
+
+(defmacro test-dev-fkeys-f4--with-project (markers &rest body)
+  "Set up a temp project with MARKERS, bind ROOT, run BODY, clean up."
+  (declare (indent 1))
+  `(let ((root (make-temp-file "test-dev-fkeys-f4-" t)))
+     (unwind-protect
+         (progn
+           (dolist (marker ,markers)
+             (write-region "" nil (expand-file-name marker root)))
+           ,@body)
+       (delete-directory root t))))
+
+;;; Normal Cases
+
+(ert-deftest test-dev-fkeys-f4-compile-and-run-prompts-with-completing-read ()
+  "Normal: the wrapper invokes completing-read with the project's candidate labels.
+
+Components integrated:
+- `cj/f4-compile-and-run' (unit under test)
+- `cj/--f4-project-root' (MOCKED — returns the temp project root)
+- `cj/--detect-project-type' (real)
+- `cj/--f4-candidates' (real)
+- `completing-read' (MOCKED — captures candidates and returns the default)
+- `cj/--f4-dispatch' (MOCKED — captures the action it received)"
+  (test-dev-fkeys-f4--with-project '("go.mod")
+    (let (seen-candidates seen-action)
+      (cl-letf (((symbol-function 'cj/--f4-project-root) (lambda () root))
+                ((symbol-function 'completing-read)
+                 (lambda (_prompt collection &rest _)
+                   (setq seen-candidates collection)
+                   (car collection)))
+                ((symbol-function 'cj/--f4-dispatch)
+                 (lambda (action) (setq seen-action action))))
+        (cj/f4-compile-and-run)
+        ;; Compiled-project candidates are the four labels.
+        (should (member "Compile + Run" seen-candidates))
+        (should (member "Compile" seen-candidates))
+        (should (member "Run" seen-candidates))
+        (should (member "Clean + Rebuild" seen-candidates))
+        ;; Default (first label) is "Compile + Run", which routes to
+        ;; the compile-and-run action.
+        (should (eq seen-action 'compile-and-run))))))
+
+(ert-deftest test-dev-fkeys-f4-compile-and-run-routes-chosen-label-to-action ()
+  "Normal: a non-default label selection routes to the right action."
+  (test-dev-fkeys-f4--with-project '("Cargo.toml")
+    (let (seen-action)
+      (cl-letf (((symbol-function 'cj/--f4-project-root) (lambda () root))
+                ((symbol-function 'completing-read)
+                 (lambda (&rest _) "Run"))
+                ((symbol-function 'cj/--f4-dispatch)
+                 (lambda (action) (setq seen-action action))))
+        (cj/f4-compile-and-run)
+        (should (eq seen-action 'run-only))))))
+
+(ert-deftest test-dev-fkeys-f4-compile-and-run-interpreted-project-shows-run-only ()
+  "Normal: an interpreted project's menu has only the Run candidate."
+  (test-dev-fkeys-f4--with-project '("pyproject.toml")
+    (let (seen-candidates)
+      (cl-letf (((symbol-function 'cj/--f4-project-root) (lambda () root))
+                ((symbol-function 'completing-read)
+                 (lambda (_prompt collection &rest _)
+                   (setq seen-candidates collection)
+                   (car collection)))
+                ((symbol-function 'cj/--f4-dispatch) (lambda (_action) nil)))
+        (cj/f4-compile-and-run)
+        (should (equal seen-candidates '("Run")))))))
+
+(provide 'test-dev-fkeys--f4-compile-and-run)
+;;; test-dev-fkeys--f4-compile-and-run.el ends here
diff --git a/tests/test-dev-fkeys--f4-compile-only.el b/tests/test-dev-fkeys--f4-compile-only.el
new file mode 100644
index 00000000..b0eec367
--- /dev/null
+++ b/tests/test-dev-fkeys--f4-compile-only.el
@@ -0,0 +1,61 @@
+;;; test-dev-fkeys--f4-compile-only.el --- Smoke tests for cj/f4-compile-only -*- lexical-binding: t -*-
+
+;;; Commentary:
+;; Smoke tests for the C-F4 fast path. On a compiled project, calls
+;; `projectile-compile-project'. On an interpreted project, messages
+;; "not a compiled language". With no project detected, falls back to
+;; plain `compile'.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'dev-fkeys)
+
+(defmacro test-dev-fkeys-co--with-project (markers &rest body)
+  "Set up a temp project with MARKERS, bind ROOT, run BODY, clean up."
+  (declare (indent 1))
+  `(let ((root (make-temp-file "test-dev-fkeys-co-" t)))
+     (unwind-protect
+         (progn
+           (dolist (marker ,markers)
+             (write-region "" nil (expand-file-name marker root)))
+           ,@body)
+       (delete-directory root t))))
+
+;;; Normal Cases
+
+(ert-deftest test-dev-fkeys-f4-compile-only-compiled-project-runs-projectile-compile ()
+  "Normal: on a compiled project, calls projectile-compile-project."
+  (test-dev-fkeys-co--with-project '("go.mod")
+    (let ((calls 0))
+      (cl-letf (((symbol-function 'cj/--f4-project-root) (lambda () root))
+                ((symbol-function 'projectile-compile-project)
+                 (lambda (_arg) (cl-incf calls))))
+        (cj/f4-compile-only)
+        (should (= calls 1))))))
+
+(ert-deftest test-dev-fkeys-f4-compile-only-interpreted-project-skips-compile ()
+  "Normal: on an interpreted project, projectile-compile-project does not run."
+  (test-dev-fkeys-co--with-project '("pyproject.toml")
+    (let ((calls 0))
+      (cl-letf (((symbol-function 'cj/--f4-project-root) (lambda () root))
+                ((symbol-function 'projectile-compile-project)
+                 (lambda (_arg) (cl-incf calls))))
+        (cj/f4-compile-only)
+        (should (= calls 0))))))
+
+;;; Boundary Cases
+
+(ert-deftest test-dev-fkeys-f4-compile-only-unknown-project-falls-back-to-compile ()
+  "Boundary: outside any project, falls back to interactive `compile'."
+  (let (received-fn)
+    (cl-letf (((symbol-function 'cj/--f4-project-root) (lambda () nil))
+              ((symbol-function 'call-interactively)
+               (lambda (fn &rest _) (setq received-fn fn))))
+      (cj/f4-compile-only)
+      (should (eq received-fn #'compile)))))
+
+(provide 'test-dev-fkeys--f4-compile-only)
+;;; test-dev-fkeys--f4-compile-only.el ends here
diff --git a/tests/test-dev-fkeys--f4-derive-clean-cmd.el b/tests/test-dev-fkeys--f4-derive-clean-cmd.el
new file mode 100644
index 00000000..9052bf55
--- /dev/null
+++ b/tests/test-dev-fkeys--f4-derive-clean-cmd.el
@@ -0,0 +1,93 @@
+;;; test-dev-fkeys--f4-derive-clean-cmd.el --- Tests for cj/--f4-derive-clean-cmd -*- lexical-binding: t -*-
+
+;;; Commentary:
+;; Tests for the heuristic clean-command picker used by M-F4
+;; (Clean + Rebuild). Returns a shell command string based on the project
+;; root's marker files, or nil when no marker matches.
+
+;;; Code:
+
+(require 'ert)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'dev-fkeys)
+
+(defmacro test-dev-fkeys-clean--with-project-dir (markers &rest body)
+  "Create a temp project dir with each filename in MARKERS as an empty file.
+Bind the dir path to ROOT in BODY. Cleans up on exit."
+  (declare (indent 1))
+  `(let ((root (make-temp-file "test-dev-fkeys-clean-" t)))
+     (unwind-protect
+         (progn
+           (dolist (marker ,markers)
+             (write-region "" nil (expand-file-name marker root)))
+           ,@body)
+       (delete-directory root t))))
+
+;;; Normal Cases
+
+(ert-deftest test-dev-fkeys-derive-clean-cmd-go-mod-uses-go-clean ()
+  "Normal: go.mod yields go clean ./..."
+  (test-dev-fkeys-clean--with-project-dir '("go.mod")
+    (should (string= (cj/--f4-derive-clean-cmd root) "go clean ./..."))))
+
+(ert-deftest test-dev-fkeys-derive-clean-cmd-cargo-toml-uses-cargo-clean ()
+  "Normal: Cargo.toml yields cargo clean."
+  (test-dev-fkeys-clean--with-project-dir '("Cargo.toml")
+    (should (string= (cj/--f4-derive-clean-cmd root) "cargo clean"))))
+
+(ert-deftest test-dev-fkeys-derive-clean-cmd-eask-uses-eask-clean ()
+  "Normal: Eask yields eask clean."
+  (test-dev-fkeys-clean--with-project-dir '("Eask")
+    (should (string= (cj/--f4-derive-clean-cmd root) "eask clean"))))
+
+(ert-deftest test-dev-fkeys-derive-clean-cmd-makefile-uses-make-clean ()
+  "Normal: Makefile yields make clean."
+  (test-dev-fkeys-clean--with-project-dir '("Makefile")
+    (should (string= (cj/--f4-derive-clean-cmd root) "make clean"))))
+
+(ert-deftest test-dev-fkeys-derive-clean-cmd-cmakelists-uses-cmake-clean ()
+  "Normal: CMakeLists.txt yields cmake build-dir clean target."
+  (test-dev-fkeys-clean--with-project-dir '("CMakeLists.txt")
+    (should (string= (cj/--f4-derive-clean-cmd root)
+                     "cmake --build build --target clean"))))
+
+;;; Boundary Cases
+
+(ert-deftest test-dev-fkeys-derive-clean-cmd-go-wins-over-makefile ()
+  "Boundary: go.mod + Makefile picks go clean (go.mod is checked first)."
+  (test-dev-fkeys-clean--with-project-dir '("go.mod" "Makefile")
+    (should (string= (cj/--f4-derive-clean-cmd root) "go clean ./..."))))
+
+(ert-deftest test-dev-fkeys-derive-clean-cmd-cargo-wins-over-makefile ()
+  "Boundary: Cargo.toml + Makefile picks cargo clean."
+  (test-dev-fkeys-clean--with-project-dir '("Cargo.toml" "Makefile")
+    (should (string= (cj/--f4-derive-clean-cmd root) "cargo clean"))))
+
+(ert-deftest test-dev-fkeys-derive-clean-cmd-eask-wins-over-makefile ()
+  "Boundary: Eask + Makefile picks eask clean."
+  (test-dev-fkeys-clean--with-project-dir '("Eask" "Makefile")
+    (should (string= (cj/--f4-derive-clean-cmd root) "eask clean"))))
+
+(ert-deftest test-dev-fkeys-derive-clean-cmd-no-markers-returns-nil ()
+  "Boundary: directory with no recognized markers returns nil."
+  (test-dev-fkeys-clean--with-project-dir '()
+    (should (null (cj/--f4-derive-clean-cmd root)))))
+
+(ert-deftest test-dev-fkeys-derive-clean-cmd-irrelevant-files-returns-nil ()
+  "Boundary: only unrelated files returns nil."
+  (test-dev-fkeys-clean--with-project-dir '("README.md" "LICENSE")
+    (should (null (cj/--f4-derive-clean-cmd root)))))
+
+;;; Error Cases
+
+(ert-deftest test-dev-fkeys-derive-clean-cmd-nil-root-returns-nil ()
+  "Error: nil ROOT returns nil with no error."
+  (should (null (cj/--f4-derive-clean-cmd nil))))
+
+(ert-deftest test-dev-fkeys-derive-clean-cmd-nonexistent-root-returns-nil ()
+  "Error: a non-existent path returns nil. file-exists-p returns nil so no
+marker matches."
+  (should (null (cj/--f4-derive-clean-cmd "/nonexistent/path/xyzzy"))))
+
+(provide 'test-dev-fkeys--f4-derive-clean-cmd)
+;;; test-dev-fkeys--f4-derive-clean-cmd.el ends here
diff --git a/tests/test-dev-fkeys--f4-dispatch.el b/tests/test-dev-fkeys--f4-dispatch.el
new file mode 100644
index 00000000..774daebf
--- /dev/null
+++ b/tests/test-dev-fkeys--f4-dispatch.el
@@ -0,0 +1,78 @@
+;;; test-dev-fkeys--f4-dispatch.el --- Tests for cj/--f4-dispatch -*- lexical-binding: t -*-
+
+;;; Commentary:
+;; Tests for the dispatch router. Each known action symbol routes to the
+;; corresponding command. Unknown actions raise user-error. The action
+;; handlers themselves are tested in their own files; this file only
+;; verifies the routing layer.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'dev-fkeys)
+
+;;; Normal Cases
+
+(ert-deftest test-dev-fkeys-dispatch-compile-only-calls-projectile-compile ()
+  "Normal: 'compile-only routes to projectile-compile-project."
+  (let ((calls 0))
+    (cl-letf (((symbol-function 'projectile-compile-project)
+               (lambda (_arg) (cl-incf calls))))
+      (cj/--f4-dispatch 'compile-only)
+      (should (= calls 1)))))
+
+(ert-deftest test-dev-fkeys-dispatch-run-only-calls-projectile-run ()
+  "Normal: 'run-only routes to projectile-run-project."
+  (let ((calls 0))
+    (cl-letf (((symbol-function 'projectile-run-project)
+               (lambda (_arg) (cl-incf calls))))
+      (cj/--f4-dispatch 'run-only)
+      (should (= calls 1)))))
+
+(ert-deftest test-dev-fkeys-dispatch-compile-and-run-routes-to-impl ()
+  "Normal: 'compile-and-run routes to cj/--f4-compile-and-run-impl."
+  (let ((calls 0))
+    (cl-letf (((symbol-function 'cj/--f4-compile-and-run-impl)
+               (lambda () (cl-incf calls))))
+      (cj/--f4-dispatch 'compile-and-run)
+      (should (= calls 1)))))
+
+(ert-deftest test-dev-fkeys-dispatch-clean-rebuild-routes-to-impl-with-root ()
+  "Normal: 'clean-rebuild routes to cj/--f4-clean-rebuild-impl with the project root.
+
+Components integrated:
+- `cj/--f4-dispatch' (unit under test)
+- `cj/--f4-project-root' (MOCKED — returns a fake path)
+- `cj/--f4-clean-rebuild-impl' (MOCKED — captures the ROOT it received)"
+  (let (received-root)
+    (cl-letf (((symbol-function 'cj/--f4-project-root)
+               (lambda () "/fake/project/"))
+              ((symbol-function 'cj/--f4-clean-rebuild-impl)
+               (lambda (root) (setq received-root root))))
+      (cj/--f4-dispatch 'clean-rebuild)
+      (should (string= received-root "/fake/project/")))))
+
+(ert-deftest test-dev-fkeys-dispatch-compile-plain-uses-call-interactively-on-compile ()
+  "Normal: 'compile-plain invokes `compile' interactively (so the user is
+prompted for a command). We check that `call-interactively' fires with
+the symbol `compile'."
+  (let (received-fn)
+    (cl-letf (((symbol-function 'call-interactively)
+               (lambda (fn &rest _) (setq received-fn fn))))
+      (cj/--f4-dispatch 'compile-plain)
+      (should (eq received-fn #'compile)))))
+
+;;; Error Cases
+
+(ert-deftest test-dev-fkeys-dispatch-unknown-action-signals-user-error ()
+  "Error: dispatch on an unknown symbol raises user-error."
+  (should-error (cj/--f4-dispatch 'fictional-action) :type 'user-error))
+
+(ert-deftest test-dev-fkeys-dispatch-nil-action-signals-user-error ()
+  "Error: nil action raises user-error (defensive against bad menu data)."
+  (should-error (cj/--f4-dispatch nil) :type 'user-error))
+
+(provide 'test-dev-fkeys--f4-dispatch)
+;;; test-dev-fkeys--f4-dispatch.el ends here
diff --git a/tests/test-dev-fkeys--f4-make-once-hook.el b/tests/test-dev-fkeys--f4-make-once-hook.el
new file mode 100644
index 00000000..b6c71dd7
--- /dev/null
+++ b/tests/test-dev-fkeys--f4-make-once-hook.el
@@ -0,0 +1,115 @@
+;;; test-dev-fkeys--f4-make-once-hook.el --- Tests for cj/--f4-make-once-hook -*- lexical-binding: t -*-
+
+;;; Commentary:
+;; Tests for the one-shot `compilation-finish-functions' hook builder used by
+;; "Compile + Run" and "Clean + Rebuild" to chain a follow-up command after
+;; a successful compile. The returned lambda:
+;;
+;; - removes itself from `compilation-finish-functions' on first invocation
+;;   regardless of status (so it never lingers across compiles)
+;; - invokes THEN-FN only when the status string indicates success — i.e.
+;;   `string-prefix-p \"finished\"' matches.
+;;
+;; The status conventions come from the compile.el infrastructure: a
+;; successful compile passes \"finished\\n\", a failed compile passes
+;; something starting with \"exited\".
+
+;;; Code:
+
+(require 'ert)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'dev-fkeys)
+
+;;; Normal Cases
+
+(ert-deftest test-dev-fkeys-make-once-hook-success-status-calls-then-fn ()
+  "Normal: status starting with 'finished' invokes THEN-FN once."
+  (let* ((called 0)
+         (hook (cj/--f4-make-once-hook (lambda () (cl-incf called)))))
+    (let ((compilation-finish-functions nil))
+      (add-hook 'compilation-finish-functions hook)
+      (funcall hook nil "finished\n"))
+    (should (= called 1))))
+
+(ert-deftest test-dev-fkeys-make-once-hook-failure-status-skips-then-fn ()
+  "Normal: status string starting with 'exited abnormally' does not invoke THEN-FN."
+  (let* ((called 0)
+         (hook (cj/--f4-make-once-hook (lambda () (cl-incf called)))))
+    (let ((compilation-finish-functions nil))
+      (add-hook 'compilation-finish-functions hook)
+      (funcall hook nil "exited abnormally with code 1\n"))
+    (should (= called 0))))
+
+(ert-deftest test-dev-fkeys-make-once-hook-success-removes-itself ()
+  "Normal: hook removes itself from `compilation-finish-functions' on success."
+  (let* ((hook (cj/--f4-make-once-hook (lambda () nil)))
+         (compilation-finish-functions (list hook)))
+    (should (memq hook compilation-finish-functions))
+    (funcall hook nil "finished\n")
+    (should-not (memq hook compilation-finish-functions))))
+
+;;; Boundary Cases
+
+(ert-deftest test-dev-fkeys-make-once-hook-failure-also-removes-itself ()
+  "Boundary: hook removes itself even on failure, so it never fires on the
+next compile. THEN-FN is not invoked, but the hook is still cleaned up."
+  (let* ((called 0)
+         (hook (cj/--f4-make-once-hook (lambda () (cl-incf called))))
+         (compilation-finish-functions (list hook)))
+    (funcall hook nil "exited abnormally with code 1\n")
+    (should (= called 0))
+    (should-not (memq hook compilation-finish-functions))))
+
+(ert-deftest test-dev-fkeys-make-once-hook-only-fires-then-fn-once ()
+  "Boundary: re-invoking the hook lambda after it self-removes does not
+re-trigger THEN-FN — the hook has been removed from the hook list and only
+external mistakes (calling the lambda directly twice) could trigger it. We
+guard against that case anyway by checking the hook removed itself, so a
+second direct funcall sees the (now-gone) hook still calls THEN-FN. This
+test documents the contract: the hook does not gate on its own state, only
+on the hook list. So the SECOND direct funcall WILL call THEN-FN. The
+guarantee in production is that `compilation-finish-functions' calls each
+hook exactly once per compile, so the practical contract is one-shot."
+  (let* ((called 0)
+         (hook (cj/--f4-make-once-hook (lambda () (cl-incf called))))
+         (compilation-finish-functions (list hook)))
+    (funcall hook nil "finished\n")
+    (funcall hook nil "finished\n")
+    (should (= called 2))))
+
+(ert-deftest test-dev-fkeys-make-once-hook-empty-status-skips-then-fn ()
+  "Boundary: empty status string does not invoke THEN-FN."
+  (let* ((called 0)
+         (hook (cj/--f4-make-once-hook (lambda () (cl-incf called)))))
+    (let ((compilation-finish-functions nil))
+      (add-hook 'compilation-finish-functions hook)
+      (funcall hook nil ""))
+    (should (= called 0))))
+
+(ert-deftest test-dev-fkeys-make-once-hook-interrupt-status-skips-then-fn ()
+  "Boundary: an 'interrupt' status (process killed) does not invoke THEN-FN."
+  (let* ((called 0)
+         (hook (cj/--f4-make-once-hook (lambda () (cl-incf called)))))
+    (let ((compilation-finish-functions nil))
+      (add-hook 'compilation-finish-functions hook)
+      (funcall hook nil "interrupt\n"))
+    (should (= called 0))))
+
+;;; Error Cases
+
+(ert-deftest test-dev-fkeys-make-once-hook-then-fn-error-still-removes-hook ()
+  "Error: if THEN-FN raises, the hook is still removed first so the
+follow-up doesn't run twice on the next compile.
+
+Components integrated:
+- `cj/--f4-make-once-hook' (the unit under test)
+- `compilation-finish-functions' (real, mutated via add-hook/remove-hook)
+- A then-fn that signals an error"
+  (let* ((hook (cj/--f4-make-once-hook (lambda () (error "boom"))))
+         (compilation-finish-functions (list hook)))
+    ;; Hook signals through the error from THEN-FN; remove-hook ran first.
+    (should-error (funcall hook nil "finished\n"))
+    (should-not (memq hook compilation-finish-functions))))
+
+(provide 'test-dev-fkeys--f4-make-once-hook)
+;;; test-dev-fkeys--f4-make-once-hook.el ends here
diff --git a/tests/test-dev-fkeys--f4-project-root.el b/tests/test-dev-fkeys--f4-project-root.el
new file mode 100644
index 00000000..617bb9e1
--- /dev/null
+++ b/tests/test-dev-fkeys--f4-project-root.el
@@ -0,0 +1,51 @@
+;;; test-dev-fkeys--f4-project-root.el --- Tests for cj/--f4-project-root -*- lexical-binding: t -*-
+
+;;; Commentary:
+;; Tests for the projectile-root wrapper. Projectile's
+;; `projectile-project-root' raises an error in some configurations when
+;; called outside a known project; this wrapper degrades to nil so the F4
+;; dispatcher can route to the 'unknown branch instead of crashing.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'dev-fkeys)
+
+;;; Normal Cases
+
+(ert-deftest test-dev-fkeys-f4-project-root-returns-projectile-value ()
+  "Normal: returns whatever `projectile-project-root' returns when fbound."
+  (cl-letf (((symbol-function 'projectile-project-root)
+             (lambda () "/some/project/")))
+    (should (string= (cj/--f4-project-root) "/some/project/"))))
+
+;;; Boundary Cases
+
+(ert-deftest test-dev-fkeys-f4-project-root-returns-nil-when-projectile-unbound ()
+  "Boundary: returns nil when projectile is not loaded.
+
+Components integrated:
+- `cj/--f4-project-root' (unit under test)
+- `projectile-project-root' (MOCKED — fmakunbound to simulate absence)"
+  (let ((had-projectile (fboundp 'projectile-project-root))
+        (saved (and (fboundp 'projectile-project-root)
+                    (symbol-function 'projectile-project-root))))
+    (unwind-protect
+        (progn
+          (when had-projectile (fmakunbound 'projectile-project-root))
+          (should (null (cj/--f4-project-root))))
+      (when had-projectile
+        (fset 'projectile-project-root saved)))))
+
+;;; Error Cases
+
+(ert-deftest test-dev-fkeys-f4-project-root-returns-nil-on-projectile-error ()
+  "Error: returns nil when `projectile-project-root' signals an error."
+  (cl-letf (((symbol-function 'projectile-project-root)
+             (lambda () (error "Outside a known project"))))
+    (should (null (cj/--f4-project-root)))))
+
+(provide 'test-dev-fkeys--f4-project-root)
+;;; test-dev-fkeys--f4-project-root.el ends here