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).

1 files changed, 78 insertions, 0 deletions

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