Fix FastHTML empty value attribute omission in select options

FastHTML omits the value attribute when value="" (empty string), causing
browsers to use the option's text content as the submitted value. This
made forms send "Keep current" or "No change" text instead of empty
string, failing Pydantic enum validation.

Fixed by using "-" as a sentinel value instead of "" for "no change"
options, and updating route handlers to treat "-" as None.

Affected forms:
- Promote form (sex, repro_status)
- Update attributes form (sex, life_stage, repro_status)
- Outcome form (yield_product_code)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/animaltrack/web/routes/actions.py

@@ -426,10 +426,13 @@ async def animal_promote(request: Request):
     form = await request.form()
 
     # Extract form data
+    # Note: "-" is used as sentinel for "no change" because FastHTML omits empty value attributes
     animal_id = form.get("animal_id", "")
     nickname = form.get("nickname", "") or None
-    sex = form.get("sex", "") or None
+    sex_raw = form.get("sex", "")
-    repro_status = form.get("repro_status", "") or None
+    sex = None if sex_raw in ("", "-") else sex_raw
+    repro_raw = form.get("repro_status", "")
+    repro_status = None if repro_raw in ("", "-") else repro_raw
     distinguishing_traits = form.get("distinguishing_traits", "") or None
     notes = form.get("notes", "") or None
     nonce = form.get("nonce")
@@ -1034,10 +1037,14 @@ async def animal_attrs(request: Request, session):
     form = await request.form()
 
     # Extract form data
+    # Note: "-" is used as sentinel for "no change" because FastHTML omits empty value attributes
     filter_str = form.get("filter", "")
-    sex = form.get("sex", "").strip() or None
+    sex_raw = form.get("sex", "").strip()
-    life_stage = form.get("life_stage", "").strip() or None
+    sex = None if sex_raw in ("", "-") else sex_raw
-    repro_status = form.get("repro_status", "").strip() or None
+    life_stage_raw = form.get("life_stage", "").strip()
+    life_stage = None if life_stage_raw in ("", "-") else life_stage_raw
+    repro_raw = form.get("repro_status", "").strip()
+    repro_status = None if repro_raw in ("", "-") else repro_raw
     roster_hash = form.get("roster_hash", "")
     confirmed = form.get("confirmed", "") == "true"
     nonce = form.get("nonce")
@@ -1277,7 +1284,9 @@ async def animal_outcome(request: Request, session):
     nonce = form.get("nonce")
 
     # Yield item fields
-    yield_product_code = form.get("yield_product_code", "").strip() or None
+    # Note: "-" is used as sentinel for "no selection" because FastHTML omits empty value attributes
+    yield_product_raw = form.get("yield_product_code", "").strip()
+    yield_product_code = None if yield_product_raw in ("", "-") else yield_product_raw
     yield_unit = form.get("yield_unit", "").strip() or None
     yield_quantity_str = form.get("yield_quantity", "").strip()
     yield_weight_str = form.get("yield_weight_kg", "").strip()

src/animaltrack/web/templates/actions.py

@@ -443,8 +443,9 @@ def promote_form(
     action_text = "Renaming" if is_rename else "Promoting"
 
     # Build sex options (optional - can refine current value)
+    # Note: Use "-" sentinel instead of "" because FastHTML omits empty value attributes
     sexes = [
-        ("", "Keep current"),
+        ("-", "Keep current"),
         ("female", "Female"),
         ("male", "Male"),
     ]
@@ -453,8 +454,9 @@ def promote_form(
         sex_options.append(Option(label, value=code, selected=code == selected_sex))
 
     # Build repro status options (optional) - must match ReproStatus enum
+    # Note: Use "-" sentinel instead of "" because FastHTML omits empty value attributes
     repro_statuses = [
-        ("", "Keep current"),
+        ("-", "Keep current"),
         ("intact", "Intact"),
         ("wether", "Wether (castrated male)"),
         ("spayed", "Spayed (female)"),
@@ -1032,24 +1034,27 @@ def attrs_form(
     )
 
     # Build sex options
+    # Note: Use "-" sentinel instead of "" because FastHTML omits empty value attributes
     sex_options = [
-        Option("No change", value="", selected=True),
+        Option("No change", value="-", selected=True),
         Option("Female", value="female"),
         Option("Male", value="male"),
         Option("Unknown", value="unknown"),
     ]
 
     # Build life stage options
+    # Note: Use "-" sentinel instead of "" because FastHTML omits empty value attributes
     life_stage_options = [
-        Option("No change", value="", selected=True),
+        Option("No change", value="-", selected=True),
         Option("Hatchling", value="hatchling"),
         Option("Juvenile", value="juvenile"),
         Option("Adult", value="adult"),
     ]
 
     # Build repro status options (intact, wether, spayed, unknown)
+    # Note: Use "-" sentinel instead of "" because FastHTML omits empty value attributes
     repro_status_options = [
-        Option("No change", value="", selected=True),
+        Option("No change", value="-", selected=True),
         Option("Intact", value="intact"),
         Option("Wether (castrated male)", value="wether"),
         Option("Spayed (female)", value="spayed"),
@@ -1293,7 +1298,8 @@ def outcome_form(
     ]
 
     # Build product options for yield items
-    product_options = [Option("Select product...", value="", selected=True)]
+    # Note: Use "-" sentinel instead of "" because FastHTML omits empty value attributes
+    product_options = [Option("Select product...", value="-", selected=True)]
     for code, name in products:
         product_options.append(Option(f"{name} ({code})", value=code))