Alembic runs one transaction PER MIGRATION, not one for the whole chain

The 2026-08-21 crash at material_items printed 'Running upgrade' lines for
location_nodes and wp_files and then rolled all three back together - env.py
wrapped the entire run in a single transaction. The repair that followed
trusted those lines: material_items was hand-created, the version stamped to
head, and production ran for two days missing two tables it claimed to have.
Found 2026-08-23 when the locations import 500'd on UndefinedTable.

transaction_per_migration=True makes the log truthful: a crash keeps every
step that completed, and a stamp-to-head repair after a crash repairs ONE
migration, not an unknowable prefix of the chain. Verified: the full chain
still applies on a fresh scratch SQLite; the offline --sql render is
unchanged.

The production surgery (creating the two rolled-back tables from the offline
postgres render) is recorded in the session; no version stamp is needed
there - it is already, now truthfully, at head.

Items: BL-027's class, third finding; env.py infrastructure.

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

docs/reference/file-map.md

@@ -292,7 +292,7 @@ Wave 8 adds these:
 ```bash
 python tests/kitting_check.py        # CR-009/010/012 - statuses, owner, delivery 26 checks
 python tests/kitting_notify_check.py # CR-011 - kitting mail, coalesced, gated    17 checks
-python tests/materials_check.py      # D6 - material list, the CR-005 pattern     17 checks
+python tests/materials_check.py      # D6 - material list, the CR-005 pattern     20 checks
 python tests/mreq_check.py           # CR-013 - lightweight request, end to end   19 checks
 ```
 

html/wp-list-import.js

@@ -105,6 +105,18 @@
       say(bits.join(''), problem);
     }
 
+    // A 500 answers plain text ("Internal Server Error"), and r.json() on that
+    // throws - which used to land in catch() and read as "could not reach the
+    // server" while the server was answering fine (found 2026-08-23, the
+    // production locations import). Read text, parse if it parses, keep status.
+    function readJson(r) {
+      return r.text().then(function (t) {
+        var j = null;
+        try { j = t ? JSON.parse(t) : null; } catch (e) { /* not JSON: a proxy or 500 page */ }
+        return { ok: r.ok, status: r.status, body: j };
+      });
+    }
+
     function importText(dryRun) {
       var text = (el(p + '-paste') || {}).value || '';
       if (!text.trim()) { say('Paste some rows or choose a CSV file first.', true); return; }
@@ -114,7 +126,7 @@
         method: 'POST', headers: { 'Content-Type': 'application/json', 'Accept': 'application/json' },
         body: JSON.stringify({ text: text, dry_run: !!dryRun }),
       })
-        .then(function (r) { return r.json().then(function (j) { return { ok: r.ok, status: r.status, body: j }; }); })
+        .then(readJson)
         .then(function (res) {
           if (!res.ok) {
             say('⚠ Import refused — ' + esc((res.body && res.body.detail) || ('HTTP ' + res.status)), true);
@@ -142,7 +154,7 @@
         method: 'POST', headers: { 'Content-Type': 'application/json', 'Accept': 'application/json' },
         body: JSON.stringify(read.payload),
       })
-        .then(function (r) { return r.json().then(function (j) { return { ok: r.ok, status: r.status, body: j }; }); })
+        .then(readJson)
         .then(function (res) {
           if (!res.ok) {
             setAddError((res.body && res.body.detail) || ('Could not add it (HTTP ' + res.status + ')'));
@@ -161,7 +173,7 @@
         method: 'PATCH', headers: { 'Content-Type': 'application/json', 'Accept': 'application/json' },
         body: JSON.stringify(patchBody),
       })
-        .then(function (r) { return r.json().then(function (j) { return { ok: r.ok, status: r.status, body: j }; }); })
+        .then(readJson)
         .then(function (res) {
           if (!res.ok) {
             say('⚠ ' + esc((res.body && res.body.detail) || ('HTTP ' + res.status)), true);

server/alembic/env.py

@@ -52,6 +52,13 @@ def run_migrations_online() -> None:
             connection=connection,
             target_metadata=target_metadata,
             compare_type=True,
+            # Each migration commits on its own. One transaction for the WHOLE
+            # run meant a crash at step N rolled back steps 1..N-1 while their
+            # "Running upgrade" lines stayed on screen claiming they ran - the
+            # 2026-08-21 outage's stamp-to-head repair trusted those lines and
+            # left production missing two tables (found 2026-08-23 when the
+            # locations import 500'd on a table that "had been created").
+            transaction_per_migration=True,
         )
         with context.begin_transaction():
             context.run_migrations()

server/app.py

@@ -2388,6 +2388,24 @@ def parse_location_rows(text: str) -> tuple[list[tuple[int, list[str]]], list[di
             rejected.append({"line": i, "text": line,
                              "reason": "no letters or digits to make a code from"})
             continue
+        # Postgres enforces VARCHAR lengths and refuses NUL/control bytes;
+        # SQLite shrugs at both - which is how ONE bad CSV line 500'd the whole
+        # production import (2026-08-23, BL-027's class again) instead of coming
+        # back as a rejection with its line number. Validate per row, here,
+        # so every dialect answers the same way: with a reason.
+        if any(any(ord(ch) < 32 for ch in p) for p in parts):
+            rejected.append({"line": i, "text": line[:120],
+                             "reason": "contains control characters — re-save the file as plain CSV (UTF-8)"})
+            continue
+        long_p = next((p for p in parts if len(p) > 200), None)
+        if long_p is not None:
+            rejected.append({"line": i, "text": line[:120],
+                             "reason": "a name is longer than 200 characters (%d)" % len(long_p)})
+            continue
+        if any(len(location_slug(p)) > 60 for p in parts):
+            rejected.append({"line": i, "text": line[:120],
+                             "reason": "a code would be longer than 60 characters"})
+            continue
         rows.append((i, parts))
     return rows, rejected
 
@@ -2454,6 +2472,7 @@ def import_locations(project_id: str, body: LocationImportIn,
     require_project_writable(db, user, project_id, "The location list cannot be changed")
 
     rows, rejected = parse_location_rows(body.text)
+    read_total = len(rows) + len(rejected)
 
     existing = {n.path: n for n in db.scalars(
         select(models.LocationNode).where(models.LocationNode.project_id == project_id)
@@ -2468,6 +2487,10 @@ def import_locations(project_id: str, body: LocationImportIn,
     for line_no, parts in rows:
         segs = [location_slug(p) for p in parts]
         full = "/".join(segs)
+        if len(full) > 200:
+            rejected.append({"line": line_no, "text": "/".join(parts)[:120],
+                             "reason": "the combined path is longer than 200 characters"})
+            continue
         if full in seen_in_file:
             duplicates.append({"line": line_no, "path": full, "names": parts,
                                "reason": "already on line %d of this import" % seen_in_file[full]})
@@ -2510,7 +2533,7 @@ def import_locations(project_id: str, body: LocationImportIn,
 
     result = {
         "project_id": project_id, "dry_run": bool(body.dry_run),
-        "read": len(rows) + len(rejected),
+        "read": read_total,
         "created": created, "duplicates": duplicates,
         "reactivated": reactivated, "rejected": rejected,
     }
@@ -3007,6 +3030,18 @@ def parse_material_rows(text: str):
             rejected.append({"line": i, "text": raw.strip()[:120],
                              "reason": "more than three columns - description, unit, code is the whole shape"})
             continue
+        # Same guard as parse_location_rows: reject what Postgres would refuse
+        # (VARCHAR limits, control bytes) with the line number, never a 500.
+        if any(any(ord(ch) < 32 for ch in p) for p in parts):
+            rejected.append({"line": i, "text": raw.strip()[:120],
+                             "reason": "contains control characters - re-save the file as plain CSV (UTF-8)"})
+            continue
+        caps = ((300, "description"), (20, "unit"), (80, "code"))
+        long_col = next((("%s is longer than %d characters (%d)" % (label, cap, len(p)))
+                         for (cap, label), p in zip(caps, parts) if len(p) > cap), None)
+        if long_col:
+            rejected.append({"line": i, "text": raw.strip()[:120], "reason": long_col})
+            continue
         rows.append((i, parts))
     return rows, rejected
 

tests/locations_check.py

@@ -323,6 +323,13 @@ def run(page, base, tok):
                 {"text": "Probe Building One,Probe Level 1,Probe Sector B"})
     chk("the import reports it as reactivated, not created or duplicate",
         len(again["body"]["reactivated"]) == 1 and not again["body"]["created"], again["body"])
+    # The 2026-08-23 production 500, pinned (locations side): Postgres-refused
+    # values reject by line, on every dialect, never crash the request.
+    hz = api(page, "POST", "/api/projects/projA/locations/import",
+             {"text": "Probe Building One," + "Y" * 220 + ",S1", "dry_run": True})
+    chk("an over-long name is a line rejection, not a 500",
+        hz["status"] == 200 and hz["body"]["rejected"]
+        and "200 characters" in hz["body"]["rejected"][0]["reason"], hz["body"])
     same = [n for n in api(page, "GET",
                            "/api/projects/projA/locations?include_inactive=true")["body"]["nodes"]
             if n["path"] == sec["path"]]

tests/materials_check.py

@@ -105,6 +105,20 @@ def main():
         _, listing = api(base, "/api/projects/projA/materials", root)
         chk("...and nothing was written", listing["items"] == [])
 
+        # The 2026-08-23 production 500, pinned: what Postgres refuses (VARCHAR
+        # overflow, control bytes) must come back as a per-line rejection - on
+        # EVERY dialect - never crash the request.
+        code, rep = api(base, "/api/projects/projA/materials/import", root, "POST",
+                        {"text": "Sample " + "x" * 300 + ",EA", "dry_run": True})
+        chk("an over-long description is a line rejection, not a 500",
+            code == 200 and rep["rejected"] and "300 characters" in rep["rejected"][0]["reason"]
+            and not rep["created"], ascii_(rep))
+        code, rep = api(base, "/api/projects/projA/materials/import", root, "POST",
+                        {"text": "Sample widget\u0000,EA", "dry_run": True})
+        chk("a control byte is a line rejection, not a 500",
+            code == 200 and rep["rejected"]
+            and "control characters" in rep["rejected"][0]["reason"], ascii_(rep))
+
         code, rep = api(base, "/api/projects/projA/materials/import", root, "POST",
                         {"text": text, "dry_run": False})
         _, listing = api(base, "/api/projects/projA/materials", root)