Track testprogram/ again, add claudeCodeChatLog.md

The test pair verify.py runs against is back in the repo, so a fresh clone
can run the built-in checks. Conversion output (*-sab2sax-*) stays ignored,
so converting inside testprogram/ still leaves the tree clean.

claudeCodeChatLog.md records how this got built: what was asked for, the
decisions worth remembering (plain paths in system.properties, the port
source, Java float formatting, the f4-rounded manifest default, why a sab
cannot return runtime props) and what is still untested.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.gitignore

@@ -1,5 +1,4 @@
 __pycache__/
 *.pyc
-testprogram/
 *-sab2sax-*.sab
 *-sab2sax-*.sax

README.md

@@ -117,9 +117,8 @@ lossy on purpose — runtime prop values and formatting are not in the binary. I
 sedonac itself wrote, they do match.)
 
 With no file argument a chooser opens, listing `.sax` and `.sab`. Cancel it and the built-in
-regression runs instead, against a `test_normal.sax` / `test_normal_sedonac.sab` pair in
+regression runs instead, against the `test_normal.sax` / `test_normal_sedonac.sab` pair checked in
-`testprogram/`. That folder is **not** in the repo (gitignored) — drop the pair in yourself,
+under `testprogram/`. Remove them and verify prints `SKIP` and exits 0 instead of failing:
-otherwise verify prints `SKIP` and exits 0:
 
     test_normal.sax -> sab            vs test_normal_sedonac.sab
     test_normal_sedonac.sab -> sax    vs test_normal.sax
@@ -142,7 +141,11 @@ Exit code is 0 on pass, 1 on failure. A malformed file fails with a one-line rea
     config.py            system.properties read/write, folder + file choosers
     verify.py            regression check against sedonac's output, both directions
     system.properties    sedona.home
-    testprogram/         local only, gitignored: test apps to run verify.py against
+    testprogram/         test apps verify.py runs against
+    claudeCodeChatLog.md how this got built, and why
+
+Conversion output (`*-sab2sax-*.sax`, `*-sab2sax-*.sab`) is gitignored, so converting inside
+`testprogram/` leaves the repo clean.
 
 ## Format
 

claudeCodeChatLog.md

@@ -0,0 +1,86 @@
+# Claude Code session log
+
+What was asked for, what was built, and the decisions behind it. Written 2026-08-13, covering the
+work that produced `ec4019e` .. `2dcc170` (tags `v0.0.0.001`, `v0.0.0.002`).
+
+Starting point: `sab.py`, a pure-Python `.sax` -> `.sab` encoder taking `<app.sax> <sedona_home>
+<out.sab>` on the command line, plus `verify.py`.
+
+## What was asked, in order
+
+1. **Sedona home into `system.properties`**, with a folder chooser on first run, and a file chooser
+   for the input.
+2. **Plain paths, not java-escaped**, in that properties file.
+3. **Timestamped output names** — `[name]-sab2sax-20260728-140609`.
+4. **The reverse direction**, `.sab` -> `.sax`, direction chosen by the input's extension.
+5. **A version**, shown in dialog titles.
+6. **`testprogram/` out of the repo** — later reversed: the test pair is checked in again, while
+   conversion output (`*-sab2sax-*`) stays gitignored.
+7. **A file chooser in `verify.py`** and a round-trip check on whatever is chosen.
+8. **A window** with a button per direction, showing the chosen file before converting and the
+   output afterwards.
+9. **`run.py`** as the entry point; log labels in capitals, values on their own lines.
+
+## What exists now
+
+    run.py               entry point: window with no arguments, CLI with them
+    gui.py               the window: a button per direction
+    sab2sax.py           the CLI: dispatches on the input extension
+    sab.py               sax -> sab encoder
+    sax.py               sab -> sax decoder
+    config.py            system.properties, dialogs, NAME/VERSION
+    verify.py            round trips + comparison against sedonac output
+    system.properties    sedona.home
+    testprogram/         test apps verify.py runs against
+
+`sedona.home` lives in `system.properties`. Missing or pointing somewhere without `manifests/` and a
+folder chooser opens, then the answer is written back. Output files are always written next to the
+input as `<stem>-sab2sax-<YYYYMMDD-HHMMSS>.<ext>`, so a run never overwrites the previous one.
+
+## Decisions worth remembering
+
+**Plain paths in `system.properties`.** Java's `Properties` (what sedonac reads it with) treats `\`
+as an escape and doubles them up; we only read the file ourselves, so we write plain Windows paths.
+The parser collapses `\\` to `\` and keeps every other backslash literal — both forms load, and
+`C:\niagara` never becomes a newline.
+
+**The decoder is a port, not a guess.** `sax.py` follows `OfflineApp.decodeAppBinary` +
+`encodeAppXml` and `OfflineComponent`/`OfflineLink` from
+`sedonaSrcOrginal/sedona/src/sedona/offline/`. The tree is rebuilt from the
+`firstChild`/`nextSibling` id chain; the XML is written the way `XWriter` does it — two-space
+indent, a `<!-- /path -->` comment above every `<comp>`, `&#x..;` escaping.
+
+**Java float formatting.** `Value.encodeString` for a float is `java.lang.Float.toString`: shortest
+digits that round-trip, always a decimal point, `E` form outside `[1e-3, 1e7)`. `sax.java_float`
+reproduces it. It matches modern Java rather than the old JDK's extra-digit quirk on subnormals
+(`1.4E-45` vs our `1.0E-45`) — only reachable with denormal floats.
+
+**The manifest default is a 32-bit float too.** A prop equal to its default is not written to the
+`.sax`. Comparing a decoded `float` against a default parsed as a Python double makes `0.1` look
+different from `0.1`, and every `minDelta="0.1"` gets written where sedonac omits it. Rounding the
+default to `f4` first was the last diff between "close" and "identical".
+
+**A `.sab` cannot give back runtime props.** Only config props are in the binary. sedonac has the
+same hole. That is why a `.sax` round trip compares the two *binaries*, not the two texts.
+
+## Verification
+
+- `test_normal.sax` -> sab, byte-identical to `test_normal_sedonac.sab` (7852 bytes)
+- `test_normal_sedonac.sab` -> sax, byte-identical to `test_normal.sax` (61294 bytes)
+- both round trips clean: `sab -> sax -> sab`, and `sax -> sab -> sax -> sab`
+
+A live `sedonac.exe` comparison was attempted and could not run here — it fails with `Cannot load
+library: C:\Program Files\Zulu\zulu-21-jre\bin\server\jvm.dll`. `verify.check_encode(sax)` /
+`check_decode(sab)` with no reference argument still do that comparison on a machine with a JRE
+sedonac will start under.
+
+Malformed input fails with one line and exit 1, not a traceback: `comp 0 app: missing child 254`.
+
+## Where to pick up
+
+- Untested paths are unchanged from before: action overrides, `Buf`-typed props, non-ASCII strings,
+  and apps whose ids exceed the 256-entry lookup table.
+- `verify.py` prints `SKIP` and exits 0 when `testprogram/` is empty rather than failing; the test
+  pair is checked in, so it normally runs.
+- Version lives in `config.py` (`NAME`, `VERSION`). The window title, every dialog title and the CLI
+  banner all read from it.