Fix native-image build and add CLAUDE.md (#63)

* Add type hints to fix native-image reflection error

BufferedWriter.write() calls used reflection which fails in GraalVM
native-image closed-world analysis. Add ^java.io.Writer type hints
at call sites so the compiler emits direct method invocations.

* Add CLAUDE.md with agent guidelines

* Address review feedback

- Remove redundant (str header) — header is already a string
- Add pre-commit hook install instructions to CLAUDE.md
- Default branch is master (not main), no change needed

* Fix pre-commit hook install command in CLAUDE.md

Use cp + chmod to match the instructions in the hook script itself.

* Use io alias consistently, remove unused trim import, add type hint comment

Author: russellwhitaker

CLAUDE.md

@@ -0,0 +1,25 @@
+# CLAUDE.md — Agent Guidelines for uap-clj
+
+## Git Workflow
+
+- **Never commit or push directly to `master`.** Always work on a feature branch.
+- Before any `git push`, verify the current branch with `git branch --show-current` and abort if on `master`.
+- Do not force-push or use `--no-verify` unless explicitly asked.
+
+## Testing
+
+- Run `clojure -T:build test` frequently — after any code change, before committing, and after merging.
+- All tests must pass before pushing.
+
+## Build & Project
+
+- Build system: deps.edn + tools.build (`build.clj`)
+- Key aliases: `:dev`, `:test`, `:build`, `:bench`
+- Build tasks: `clojure -T:build test`, `clojure -T:build uber`, `clojure -T:build native-image`
+- Formatting: cljstyle (runs via pre-commit hook in `hooks/pre-commit`; install with `cp hooks/pre-commit .git/hooks/pre-commit && chmod +x .git/hooks/pre-commit`)
+- Native image requires GraalVM with `native-image` on PATH
+
+## Deploy
+
+- Clojars deploy requires `-Djava.net.preferIPv4Stack=true` (already in `:build` alias JVM opts)
+- Use `clojure -T:build deploy` to publish to Clojars

src/uap_clj/core.clj

@@ -3,7 +3,7 @@
   (:gen-class)
   (:require
    [clojure.java.io :as io]
-   [clojure.string :as s :refer [join trim]]
+   [clojure.string :as s :refer [join]]
    [uap-clj.browser :refer [browser]]
    [uap-clj.common :as common :refer :all]
    [uap-clj.conf :refer [load-config]]
@@ -51,16 +51,18 @@
    'useragent_lookup.tsv' is the name of the default output file.
   "
   [in-file & opt-args]
-  (with-open [rdr (clojure.java.io/reader in-file)]
+  (with-open [rdr (io/reader in-file)]
     (let [out-file (or (first opt-args)
                        (:output-filename cfg))
           results (doall
                    (map useragent (line-seq rdr)))]
       (with-open
-       [wtr (clojure.java.io/writer out-file :append false)]
-        (.write wtr header)
+       ;; Type hints must be per-call: with-open macro expansion drops
+       ;; binding-level hints, causing reflection failures in native-image.
+       [wtr (io/writer out-file :append false)]
+        (.write ^java.io.Writer wtr header)
         (doseq [ua results]
-          (.write wtr
+          (.write ^java.io.Writer wtr
                   (str (s/join \tab
                                (map #(get-in ua %) columns))
                        \newline)))))))