fix: stop asking for dumps the collection can make

The Wanted page listed 79 dumps the collection already produces,
such as a Kickstart's byte-swapped words or the halves of a C128
character ROM. The pipeline now records which missing dumps can be
derived, in derivable.json, and the page moves them to a section of
their own that names the held file and the transform.

.github/workflows/deploy-site.yml

@@ -51,6 +51,7 @@ on:
       - "install.py"
       - "database.json"
       - "release.json"
+      - "derivable.json"
       - "mkdocs.yml"
       - ".github/workflows/deploy-site.yml"
   workflow_dispatch:

derivable.json

@@ -0,0 +1,486 @@
+{
+  "03df800f032046fd892f6e7eec08b76d33981e8c": {
+    "from": [
+      "bios/Arcade/MAME/amiga_a570.zip/391298-01_v230.u20"
+    ],
+    "transform": "odd bytes"
+  },
+  "052ac869da3764b44031328cd584985f705a6516": {
+    "from": [
+      "bios/Enterprise/64-128/basic10.bin"
+    ],
+    "transform": "first half"
+  },
+  "05ff9debbb0c6a2e446243dbb58b192ec901af7e": {
+    "from": [
+      "bios/Arcade/MAME/everdrive_md.zip/v35.bin"
+    ],
+    "transform": "second half"
+  },
+  "0735ecfafd151cb7bb4c09748c0eb5de54321e93": {
+    "from": [
+      "bios/Arcade/Arcade/famicom.zip/famitvc1/ix0402ce.ic109",
+      "bios/Arcade/Arcade/famicom.zip/famitvc1/ix0403ce.ic110"
+    ],
+    "transform": "concatenated"
+  },
+  "08c702b45017641cf7bb2d23334509c2f7dd35d3": {
+    "from": [
+      "bios/Commodore/Amiga/kick31034.A1000"
+    ],
+    "transform": "mirrored twice"
+  },
+  "09fc005625589ef5992515957ce7a3167dec24b2": {
+    "from": [
+      "bios/Other/zesarux/p2as.rom"
+    ],
+    "transform": "quarter 3"
+  },
+  "0a2f67455166f8dac101f8f8564a1c0364cb456a": {
+    "from": [
+      "bios/Commodore/C128/vice/C128/kernalfr"
+    ],
+    "transform": "quarter 1"
+  },
+  "0b0e7571c8ab7a18a1d1c5e7181cb5dac372daac": {
+    "from": [
+      "bios/Arcade/Namco System 246/COH-H31000.BIN"
+    ],
+    "transform": "first half"
+  },
+  "0be048cd378625afd99338ada53bde434cc4613f": {
+    "from": [
+      "bios/Commodore/C128/vice/PET/basic-2.901465-01-02.bin"
+    ],
+    "transform": "quarter 4"
+  },
+  "0d1c771d8c836cd010cb06434accba2a5532f7f9": {
+    "from": [
+      "bios/Other/citron/switch/key_retail.bin"
+    ],
+    "transform": "first half"
+  },
+  "1330580c0614d3556a389da4649488ba04a60908": {
+    "from": [
+      "bios/Commodore/C128/vice/PET/basic-1.901439-09-05-02-06.bin"
+    ],
+    "transform": "quarter 1"
+  },
+  "196e9f3f9cad934e181c07da33083b1f0a3c702f": {
+    "from": [
+      "bios/Commodore/Amiga/kick39106.A4000"
+    ],
+    "transform": "even words, byte-swapped"
+  },
+  "1bc0ebf27c9bb62ad71bca40313e874234cab6ac": {
+    "from": [
+      "bios/Commodore/C128/vice/PET/basic-2.901465-01-02.bin"
+    ],
+    "transform": "second half"
+  },
+  "1f5abdcbb305e08ca3d352eadcff6a58542d86d7": {
+    "from": [
+      "bios/Commodore/C128/vice/PET/basic-2.901465-01-02.bin"
+    ],
+    "transform": "quarter 3"
+  },
+  "21a90256a3572a890f8027a085d851bf818b0dda": {
+    "from": [
+      "bios/Commodore/C128/vice/C128/kernalno"
+    ],
+    "transform": "second half"
+  },
+  "22f6c5f40d4e895ea51e8432b30c219eacb75778": {
+    "from": [
+      "bios/Commodore/C128/vice/C128/kernalno"
+    ],
+    "transform": "quarter 1"
+  },
+  "24e52b5efc02049517387ab7b1a1475fc540350e": {
+    "from": [
+      "bios/Commodore/Amiga/amiga-os-310-a4000.rom"
+    ],
+    "transform": "even words, byte-swapped"
+  },
+  "2920cdaf1fda0b54b1e0e53736f936b853716988": {
+    "from": [
+      "bios/Arcade/Arcade/mz800.zip/mz800.rom"
+    ],
+    "transform": "quarter 1"
+  },
+  "2e51c562ef5ae6aa4cd333c560afed0c34902e28": {
+    "from": [
+      "bios/Commodore/C128/vice/C128/kernalfi"
+    ],
+    "transform": "second half"
+  },
+  "313c7cbda5779e56f19a41d34e760f517626d882": {
+    "from": [
+      "bios/Commodore/Amiga/amiga-os-310-a4000.rom"
+    ],
+    "transform": "odd words, byte-swapped"
+  },
+  "3341108d3a402882b5ef9d3b242cbf3c8ab1a3e9": {
+    "from": [
+      "bios/Commodore/Amiga/kick39106.A1200"
+    ],
+    "transform": "odd words, byte-swapped"
+  },
+  "33777c133c76436a55ada7041eedb0ce76991984": {
+    "from": [
+      "bios/Arcade/MAME/spectrum_opus.zip/24.ic8"
+    ],
+    "transform": "mirrored twice"
+  },
+  "3622111f486d0e137022523657394befa92bde44": {
+    "from": [
+      "bios/Commodore/C128/vice/PET/basic-2.901465-01-02.bin"
+    ],
+    "transform": "first half"
+  },
+  "38662a024f1de2f4417a5f9df4898a9985503e06": {
+    "from": [
+      "bios/Commodore/C128/JiffyDOS_C128.bin"
+    ],
+    "transform": "quarter 2"
+  },
+  "39add4c0adda7a64f68a09ae8742599091228017": {
+    "from": [
+      "bios/Commodore/C128/vice/C128/kernalit"
+    ],
+    "transform": "quarter 1"
+  },
+  "3ac4b9ae895c45630d10cfc9079f5dcbce5eb48e": {
+    "from": [
+      "bios/Arcade/Arcade/pet_superpet.zip/901898-03.u19",
+      "bios/Arcade/Arcade/pet_superpet.zip/901898-04.u20"
+    ],
+    "transform": "concatenated"
+  },
+  "3eba870bcb2c5efa906f2ca3febe960fc35d66bb": {
+    "from": [
+      "bios/Other/zesarux/plus2c.rom"
+    ],
+    "transform": "first half"
+  },
+  "3fcdfa96f862b0cb7603fb6c2af84cac59527b05": {
+    "from": [
+      "bios/Philips/CD-i/cdi910.zip/cdi910.rom"
+    ],
+    "transform": "byte-swapped"
+  },
+  "401270052aebac24c8321f2c7436828b08185a00": {
+    "from": [
+      "bios/Commodore/C128/vice/C128/basichi-318019-04.bin",
+      "bios/Commodore/C128/vice/C128/basiclo-318018-04.bin"
+    ],
+    "transform": "concatenated"
+  },
+  "4081e365ff53bd5b8675a232a4793f6a1d087543": {
+    "from": [
+      "bios/Commodore/C128/vice/PET/kernal-2.901465-03.bin"
+    ],
+    "transform": "second half"
+  },
+  "42e7909e0198701102ec19b1bf66c240dd3fa8b3": {
+    "from": [
+      "bios/Arcade/MAME/manager.zip/01",
+      "bios/Arcade/MAME/manager.zip/23"
+    ],
+    "transform": "concatenated"
+  },
+  "42fbed3453d1f11ccbde89a9826f2d1175cca5cc": {
+    "from": [
+      "bios/Commodore/Amiga/kick39106.A4000"
+    ],
+    "transform": "odd words, byte-swapped"
+  },
+  "446ae58f7110d74d434301491209299f66798d8a": {
+    "from": [
+      "bios/Commodore/C128/vice/C128/chargen-325181-01.bin"
+    ],
+    "transform": "second half"
+  },
+  "4708d6678cfff5be9b6a217aa45102d4f4dc20c7": {
+    "from": [
+      "bios/Commodore/C128/vice/C128/basic-901226-01.bin",
+      "bios/Commodore/C128/vice/C128/kernal64-325179-01.bin"
+    ],
+    "transform": "concatenated"
+  },
+  "4990536c7f77e1025c90f0541a73bd157210efc9": {
+    "from": [
+      "bios/Other/zesarux/plus2b.rom"
+    ],
+    "transform": "first half"
+  },
+  "4b0a38b5af525aa598907683f0dcfeaa90d242e0": {
+    "from": [
+      "bios/Arcade/Arcade/channelf.zip/sl31253.rom",
+      "bios/Arcade/Arcade/channelf.zip/sl31254.rom"
+    ],
+    "transform": "concatenated"
+  },
+  "4bf2c20c51a63d213886957485ebef336bb803d0": {
+    "from": [
+      "bios/Commodore/C128/vice/PET/basic-1.901439-09-05-02-06.bin"
+    ],
+    "transform": "quarter 3"
+  },
+  "4e48f196427596c7990c175d135c15a039c274a4": {
+    "from": [
+      "bios/Other/zesarux/p2as.rom"
+    ],
+    "transform": "quarter 2"
+  },
+  "4f41f85124a682b0243e9d64a5f7f6a99258ea20": {
+    "from": [
+      "bios/Arcade/Arcade/msx_cart_bm_012.zip/midi_v1.00.u4"
+    ],
+    "transform": "quarter 1"
+  },
+  "549460542269e41036018402e1f6b855fd89092b": {
+    "from": [
+      "bios/Arcade/MAME/amiga_a570.zip/391298-01_v230.u20"
+    ],
+    "transform": "even bytes"
+  },
+  "56684c4c85a616e726a50707483b9a42d8e724ed": {
+    "from": [
+      "bios/Other/zesarux/p2f.rom"
+    ],
+    "transform": "first half"
+  },
+  "5ab17ee70467152bf2130e3f48a2aa81e9df93c9": {
+    "from": [
+      "bios/Commodore/C128/vice/PET/basic-4.901465-23-20-21.bin",
+      "bios/Commodore/C128/vice/PET/kernal-4.901465-22.bin"
+    ],
+    "transform": "concatenated"
+  },
+  "5f02e97b48ebbba87d516a56b0400c6fc3434d8d": {
+    "from": [
+      "bios/Commodore/Amiga/amiga-os-310-a3000.rom"
+    ],
+    "transform": "odd words, byte-swapped"
+  },
+  "603ba1e5967ca6298ff598ced18b28439fbc027f": {
+    "from": [
+      "bios/Arcade/MAME/spectrum_opus.zip/gamma.bin"
+    ],
+    "transform": "second half"
+  },
+  "6763a2258ec493f7408cf663110dae9a17803ad1": {
+    "from": [
+      "bios/Commodore/Amiga/amiga-os-310-a3000.rom"
+    ],
+    "transform": "even words, byte-swapped"
+  },
+  "699ce22561ed85351e833019771f8375454a063b": {
+    "from": [
+      "bios/Microsoft/MSX/Shared Roms/MSX2R.rom"
+    ],
+    "transform": "first half"
+  },
+  "70c0f4fa67a70995b168668c957c3fcf2c8641bd": {
+    "from": [
+      "bios/Commodore/C128/vice/PET/basic-1.901439-09-05-02-06.bin"
+    ],
+    "transform": "quarter 2"
+  },
+  "7551f74cc332f20923c36b24ae0ad3274f74ec37": {
+    "from": [
+      "bios/Enterprise/64-128/basic10.bin"
+    ],
+    "transform": "second half"
+  },
+  "765372a0e16cbb0adf23a07b80f6b682b39fbf88": {
+    "from": [
+      "bios/Commodore/C128/vice/C128/basic-901226-01.bin",
+      "bios/Commodore/C128/vice/C128/kernal-901227-03.bin"
+    ],
+    "transform": "concatenated"
+  },
+  "7e398f62689c9d90a36d3a101351ec9987207308": {
+    "from": [
+      "bios/Other/zesarux/p2f.rom"
+    ],
+    "transform": "second half"
+  },
+  "8259241b28ff85441f1bedc2bee53445767c51c5": {
+    "from": [
+      "bios/Other/zesarux/p2s.rom"
+    ],
+    "transform": "first half"
+  },
+  "89639e3dbf517eeac7b307ba59df708c99728e66": {
+    "from": [
+      "bios/Commodore/C128/vice/PET/basic-2.901465-01-02.bin"
+    ],
+    "transform": "quarter 2"
+  },
+  "8b26c86586787cd615c72f858307d18147872fb3": {
+    "from": [
+      "bios/Commodore/C128/vice/PET/basic-2.901465-01-02.bin"
+    ],
+    "transform": "quarter 1"
+  },
+  "90e331be1970b0e53f53a9b0390b51b59b3869c2": {
+    "from": [
+      "bios/Commodore/Amiga/amiga-os-310-a1200.rom"
+    ],
+    "transform": "odd words, byte-swapped"
+  },
+  "953dcdf5784a6b39ef84dd6fd968c7a03d8d6816": {
+    "from": [
+      "bios/Commodore/C128/vice/C128/basiclo-318018-04.bin",
+      "bios/Commodore/C128/vice/C128/basichi-318019-04.bin"
+    ],
+    "transform": "concatenated"
+  },
+  "960717282878e7de893d87242ddf9d1512be162e": {
+    "from": [
+      "bios/Commodore/C128/vice/PET/kernal-1.901439-04-07.bin"
+    ],
+    "transform": "first half"
+  },
+  "97f5916d9877b5bac9fa7bc1dd724a4d10212208": {
+    "from": [
+      "bios/Other/zesarux/plus2b.rom"
+    ],
+    "transform": "quarter 3"
+  },
+  "999eb81c65dfd07a71ee19315d99c7eb858ab186": {
+    "from": [
+      "bios/Commodore/Amiga/kick39106.A1200"
+    ],
+    "transform": "even words, byte-swapped"
+  },
+  "a7f06facc6f0a3713215f4befc307914836706a4": {
+    "from": [
+      "bios/Other/speccy/COUPE.ROM"
+    ],
+    "transform": "second half"
+  },
+  "ad676ac04c6e7861924093654bd67ff4807ebc53": {
+    "from": [
+      "bios/Other/citron/switch/key_retail.bin"
+    ],
+    "transform": "second half"
+  },
+  "b1caa56044db8731f9959d78abd7d4194fb39c0a": {
+    "from": [
+      "bios/Other/zesarux/plus2b.rom"
+    ],
+    "transform": "quarter 4"
+  },
+  "b8800f5f909298109ea69690b1b8523fa22ddb37": {
+    "from": [
+      "bios/Commodore/Amiga/amiga-os-310-a1200.rom"
+    ],
+    "transform": "even words, byte-swapped"
+  },
+  "d234a031caf59a0f66871f2babe1644783e66cf7": {
+    "from": [
+      "bios/Commodore/C128/vice/C128/kernalfr"
+    ],
+    "transform": "second half"
+  },
+  "d293972d529023d8fd1f493149e4777b5c253a69": {
+    "from": [
+      "bios/Commodore/C128/vice/PET/basic-1.901439-09-05-02-06.bin"
+    ],
+    "transform": "quarter 4"
+  },
+  "d440f2510bc52e20c3d6bc8b9ded9cea7f462a9c": {
+    "from": [
+      "bios/Commodore/C128/vice/PET/kernal-1.901439-04-07.bin"
+    ],
+    "transform": "second half"
+  },
+  "d92e3fd2a65dbf439d7050d9cea732a63640d567": {
+    "from": [
+      "bios/Other/zesarux/samcoupe.rom"
+    ],
+    "transform": "first half"
+  },
+  "dcd18397dd2a691118aaacf2b087d08e3782f81a": {
+    "from": [
+      "bios/Arcade/Arcade/pet_superpet.zip/901898-01.u17",
+      "bios/Arcade/Arcade/pet_superpet.zip/901898-02.u18"
+    ],
+    "transform": "concatenated"
+  },
+  "e0771493503225d309e51239249e8d92da55ca37": {
+    "from": [
+      "bios/Commodore/C128/vice/C128/kernalfi"
+    ],
+    "transform": "quarter 1"
+  },
+  "e0e99cd91e88ce2676445663f832c835d74d6fd4": {
+    "from": [
+      "bios/Arcade/Arcade/msx.zip/kanji.rom"
+    ],
+    "transform": "first half"
+  },
+  "e1d062ae209ad0257e1b743718d210b1c83d8035": {
+    "from": [
+      "bios/Commodore/Amiga/kick32034.A1000"
+    ],
+    "transform": "mirrored twice"
+  },
+  "e9b0a60a1a8def511d59090b945d175bdc646346": {
+    "from": [
+      "bios/Other/zesarux/p2as.rom"
+    ],
+    "transform": "quarter 1"
+  },
+  "ec0d5a158842d20601b4fbeaefc6668db979d0e1": {
+    "from": [
+      "bios/Other/zesarux/p2s.rom"
+    ],
+    "transform": "second half"
+  },
+  "ec8f644a81e2e9bcb58ace974103ea960361bad2": {
+    "from": [
+      "bios/Other/zesarux/p2as.rom"
+    ],
+    "transform": "quarter 4"
+  },
+  "ecbddfa12ca44bc7aae7a12d13c6c0bd10066362": {
+    "from": [
+      "bios/Microsoft/MSX/MSX2R2.ROM"
+    ],
+    "transform": "second half"
+  },
+  "f27bb2ba0f4c7b9e8c6b997eefe5a21ebec80c71": {
+    "from": [
+      "bios/Arcade/MAME/spectrum_opus.zip/gamma.bin"
+    ],
+    "transform": "first half"
+  },
+  "f5d604d89daedb47a1abe4b0aa41ea762829e71e": {
+    "from": [
+      "bios/Commodore/C128/vice/C128/kernalit"
+    ],
+    "transform": "second half"
+  },
+  "f69252609e587d4fb5713ef834b63e8a70ffd82a": {
+    "from": [
+      "bios/Other/zesarux/plus2b.rom"
+    ],
+    "transform": "quarter 1"
+  },
+  "f71be031a5dfa837de225081b2ddc8dcb74a0552": {
+    "from": [
+      "bios/Philips/CD-i/cdi490a.zip/cdi490a.rom"
+    ],
+    "transform": "byte-swapped"
+  },
+  "fcc939d58c9bda5b54d6fb818ed4d0804e5ac377": {
+    "from": [
+      "bios/Commodore/C128/vice/PET/kernal-2.901465-03.bin"
+    ],
+    "transform": "first half"
+  }
+}

scripts/generate_site.py

@@ -1690,7 +1690,22 @@ def _prov_title(data: dict) -> str:
     return ": ".join(p for p in parts if p).replace('"', """)
 
 
-def generate_provenance_page(db: dict, report: dict) -> str:
+def load_derivable(path: str = "derivable.json") -> dict[str, dict]:
+    """Missing sha1 -> how the collection produces it, as the pipeline found.
+
+    Empty when the pipeline has not recorded it: the page then lists every
+    missing dump, as it did before the record existed.
+    """
+    try:
+        with open(path, encoding="utf-8") as handle:
+            return json.load(handle)
+    except FileNotFoundError:
+        return {}
+
+
+def generate_provenance_page(
+    db: dict, report: dict, derivable: dict[str, dict] | None = None
+) -> str:
     """Page explaining the verified dump badges and listing catalog gaps."""
     matched_files = count_catalog_matched(db)
     total_files = compute_composition(db)["systems"]["files"]
@@ -1774,6 +1789,20 @@ def generate_provenance_page(db: dict, report: dict) -> str:
             ]
         )
 
+    # A dump the collection already produces (the odd bytes of a Kickstart,
+    # the halves of a character ROM) is no acquisition target: the page asked
+    # the public for 79 of them.
+    derivable = derivable or {}
+    derived_entries: dict[str, dict] = {}
+    for data in report.values():
+        kept = []
+        for entry in data["missing"]:
+            sha1 = (entry.get("sha1") or "").lower()
+            if sha1 in derivable:
+                derived_entries.setdefault(sha1, entry)
+            else:
+                kept.append(entry)
+        data["missing"] = kept
     total_missing = distinct_missing(report)
     lines.extend(
         [
@@ -1811,6 +1840,26 @@ def generate_provenance_page(db: dict, report: dict) -> str:
                 lines.append(f"    | `{name}` | {desc} | `{sha1}` |")
             lines.append("")
 
+    if derived_entries:
+        lines.extend(
+            [
+                "## Derivable: dumps the collection already produces",
+                "",
+                f"**{len(derived_entries):,}** catalogued dumps are not held as "
+                "files but come out of one that is: a byte or word split, a "
+                "half, a swap, or two chips joined. They are not wanted.",
+                "",
+                "| Name | Comes from | How | SHA1 |",
+                "|------|------------|-----|------|",
+            ]
+        )
+        for sha1, entry in sorted(derived_entries.items(), key=lambda kv: kv[1]["name"]):
+            how = derivable[sha1]
+            sources = " + ".join(f"`{path}`" for path in how.get("from", []))
+            name = entry["name"].replace("|", "-")
+            lines.append(f"| `{name}` | {sources} | {how.get('transform', '')} | `{sha1}` |")
+        lines.append("")
+
     lines.append(f'<div class="rb-timestamp">Generated on {_timestamp()}.</div>')
     return "\n".join(lines) + "\n"
 
@@ -3927,7 +3976,8 @@ def main() -> None:
     print("Generating dump provenance page...")
     provenance_report = build_report(db, load_provenance_snapshots())
     write_if_changed(
-        str(docs / "provenance.md"), generate_provenance_page(db, provenance_report)
+        str(docs / "provenance.md"),
+        generate_provenance_page(db, provenance_report, load_derivable()),
     )
 
     # Wiki pages: copy manually maintained sources + generate dynamic ones

scripts/pipeline.py

@@ -3,7 +3,7 @@
 
 Steps:
   1. generate_db.py --force     (rebuild database.json from bios/)
-  1b. provenance_report.py      (dump-catalog coverage from provenance/)
+  1b. provenance_report.py      (dump-catalog coverage, derivable.json)
   1c. romset_recipes.py         (archive identification, reconstruction targets)
   2. refresh_data_dirs.py       (update Dolphin Sys, PPSSPP, etc.)
   2b2. check_release_assets.py  (large-files release vs gitignored files, online)
@@ -400,9 +400,12 @@ def main() -> None:
         print("\nDatabase generation failed, aborting.")
         sys.exit(1)
 
-    # Step 1b: Dump-catalog coverage (offline, reads provenance/ snapshots)
+    # Step 1b: Dump-catalog coverage (offline, reads provenance/ snapshots),
+    # and which missing dumps the collection already produces: recorded in
+    # derivable.json, which the site reads instead of rereading bios/.
     ok, _ = run(
-        [sys.executable, "scripts/provenance_report.py"],
+        [sys.executable, "scripts/provenance_report.py", "--derive",
+         "--write-derivable", "derivable.json"],
         "1b provenance report",
     )
     results["provenance"] = ok

scripts/provenance_report.py

@@ -22,7 +22,12 @@ import sys
 import zipfile
 
 sys.path.insert(0, os.path.dirname(__file__))
-from common import DEFAULT_PROVENANCE_DIR, load_database, load_provenance_snapshots
+from common import (
+    DEFAULT_PROVENANCE_DIR,
+    load_database,
+    load_provenance_snapshots,
+    write_if_changed,
+)
 
 
 def archive_members(db: dict) -> dict[tuple[str, int], list[tuple[str, str]]]:
@@ -176,7 +181,15 @@ def main() -> int:
         "byte swaps, concatenations); reads the collection, about 90 s",
     )
     parser.add_argument("--json", action="store_true", help="Full report as JSON")
+    parser.add_argument(
+        "--write-derivable",
+        metavar="PATH",
+        help="With --derive, record the derivable entries for the site "
+        "(the pipeline writes derivable.json)",
+    )
     args = parser.parse_args()
+    if args.write_derivable and not args.derive:
+        parser.error("--write-derivable records what --derive finds; pass both")
 
     db = load_database(args.db)
     snapshots = load_provenance_snapshots(args.provenance_dir)
@@ -195,6 +208,14 @@ def main() -> int:
                 e["sha1"]: derived[e["sha1"]] for e in data["missing"]
                 if e.get("sha1") in derived
             }
+        if args.write_derivable:
+            # The site cannot spend 80 s reading the collection on every
+            # build: the pipeline records what this pass found, and the
+            # Wanted page stops asking for dumps the collection can produce.
+            write_if_changed(
+                args.write_derivable,
+                json.dumps(dict(sorted(derived.items())), indent=2, sort_keys=True) + "\n",
+            )
 
     if args.json:
         print(json.dumps(report, indent=2))

tests/test_provenance.py

@@ -534,5 +534,31 @@ class OneDumpIsCountedOnce(unittest.TestCase):
         self.assertEqual(provenance_report.distinct_missing(twice), 1)
 
 
+class TheWantedPageAsksOnlyForWhatCannotBeMade(unittest.TestCase):
+    """The site's Wanted page asked the public for 79 dumps the collection
+    already produces (a Kickstart's odd bytes, a character ROM's halves)."""
+
+    def test_a_derivable_dump_moves_out_of_the_wanted_list(self):
+        from scripts import generate_site  # noqa: PLC0415
+
+        report = {"tosec": {
+            "imported_at": "2026-01-01", "dats": {}, "total": 2, "matched": 0,
+            "covered_dats": ["Commodore Amiga - Firmware"], "out_of_scope": 0,
+            "missing": [
+                {"name": "kick31.rom", "sha1": "a" * 40, "dat": "Commodore Amiga - Firmware"},
+                {"name": "lost.rom", "sha1": "b" * 40, "dat": "Commodore Amiga - Firmware"},
+            ],
+        }}
+        derivable = {"a" * 40: {"from": ["bios/Commodore/Amiga/a1200.rom"],
+                                "transform": "byte swap"}}
+        page = generate_site.generate_provenance_page({"files": {}}, report, derivable)
+        wanted, _, derived = page.partition("## Derivable")
+        self.assertIn("**1** dumps a catalog", wanted)
+        self.assertNotIn("kick31.rom", wanted)
+        self.assertIn("lost.rom", wanted)
+        self.assertIn("kick31.rom", derived)
+        self.assertIn("byte swap", derived)
+
+
 if __name__ == "__main__":
     unittest.main()