From b01d54d926e774c3ffa586bd2bc6d423061715e2 Mon Sep 17 00:00:00 2001
From: Mark Ridley <210189+maudlin@users.noreply.github.com>
Date: Mon, 22 Jun 2026 23:22:29 +0100
Subject: [PATCH] =?UTF-8?q?feat(scc):=20generated-marker=20exclusion=20?=
 =?UTF-8?q?=E2=80=94=20banner-shaped,=20opt-in,=20enumerated=20(#114)?=
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Phase 2 of plan 0002 (#107), on the merged Phase 1 routing. With
CHECKUP_EXCLUDE_GENERATED=1, drop files whose head carries a banner-shaped
generated marker from BOTH the lizard inventory and the scc keep-set — the
corvus lever (39,208 -> 3,569 source files; 41,081 -> 5,442 keep-set), which
also pre-empts the #105 lizard blow-ups by shrinking the set first.

- lib/source-inventory.sh: INV_GENERATED_RE (Go `Code generated … DO NOT
  EDIT.`, comment-leader `@generated`, C# `<auto-generated>`) +
  _apply_generated_excludes, called from build_source_inventory and
  build_scc_keepset (mirrors _apply_gitattr_excludes). Markers are
  case-sensitive + anchored (NOT the spike's loose substrings) so first-party
  code that quotes a marker, or owns a bare `DO NOT EDIT` (IaC, migrations),
  is kept (Morlock M1). Whole-file `grep -lIZ` short-circuits at the marker
  (cheap even on mostly-generated trees) and catches markers below line 1
  (corvus's sit on line 2). Every drop is ENUMERATED to `<lst>.generated`
  (loud, not a silent count); sets GENERATED_EXCLUDED_COUNT.

- Opt-in (default off) so the regex is field-tested with zero default-
  behaviour change; flip to default-on is a deliberate follow-up. Surfacing
  "% generated" as a headline signal is Phase 3.

- test/source-inventory.test.sh: opt-in off = unchanged; on = drops the three
  banner forms, keeps prose/bare-DO-NOT-EDIT first-party, sets the count, and
  enumerates the drops.

Refs #107.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 CHANGELOG.md                  | 11 ++++++++++
 lib/source-inventory.sh       | 40 +++++++++++++++++++++++++++++++++++
 test/source-inventory.test.sh | 32 ++++++++++++++++++++++++++++
 3 files changed, 83 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6ade7f8..f02fc6d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,17 @@ across the whole thing, honestly*.
 
 ### Added
 
+- **Generated-marker exclusion (opt-in)** (#114, plan 0002 Phase 2): with
+  `CHECKUP_EXCLUDE_GENERATED=1`, files whose head carries a **banner-shaped**
+  generated marker (Go `// Code generated … DO NOT EDIT.`, a comment-leader
+  `@generated`, or C# `<auto-generated>`) are dropped from **both** the lizard
+  inventory and the scc keep-set — the lever that stops a codegen-heavy repo from
+  drowning the measurement (corvus: 39,208 → 3,569 source files) and pre-empts the
+  #105 lizard blow-ups. Markers are case-sensitive and anchored (not the loose
+  substrings a draft used), so first-party code that merely *quotes* a marker — or
+  owns a bare `DO NOT EDIT` (IaC, hand-written migrations) — is kept. Every drop is
+  **enumerated** to `raw/…​.generated` (loud, not a silent count). Default off until
+  field-tested; surfacing "% generated" as a headline signal is Phase 3.
 - **First-party source — the scc-based engines honour the inventory** (#109,
   plan 0002 Phase 1; closes #18): `codebase-stats`, stack-identity, the scc
   complexity arm and tech-viability now filter + re-aggregate a single
diff --git a/lib/source-inventory.sh b/lib/source-inventory.sh
index c965acc..53871c3 100644
--- a/lib/source-inventory.sh
+++ b/lib/source-inventory.sh
@@ -34,6 +34,17 @@ INV_JSTS_RE='\.(ts|tsx|js|jsx|mjs|cjs|svelte|vue)$'
 INV_NONJS_RE='\.(py|cs|java|kt|kts|go|rb|php|rs|c|cc|cpp|cxx|h|hpp|m|mm|swift|scala|lua)$'      # lizard's non-JS slice (#68)
 INV_LIZARD_RE='\.(ts|tsx|js|jsx|py|cs|java|kt|kts|go|rb|php|rs|c|cc|cpp|cxx|h|hpp|m|mm|swift|scala|lua)$'  # everything lizard tokenises
 
+# Generated-file markers (#114, plan 0002 Phase 2). BANNER-SHAPED + case-sensitive,
+# NOT loose substrings: the spike's `@generated|DO NOT EDIT|…` (case-insensitive)
+# fired on first-party code that merely *mentions* a marker (codegen tooling,
+# Flow/Relay, lint configs) or owns it (IaC `# DO NOT EDIT`, hand-written
+# migrations) — Morlock M1. Three anchored forms, matched as whole comment lines:
+#   1. Go canonical:   `// Code generated <by …>. DO NOT EDIT.`  (full line)
+#   2. `@generated`:    only inside a comment leader at line start (//, #, *, /*, --, <!--)
+#   3. C# designer:     `<auto-generated>` at line start (optionally `// `-prefixed)
+# Bare `DO NOT EDIT` is deliberately NOT a marker (too weak; it owns IaC/migrations).
+INV_GENERATED_RE='^//[[:space:]]*Code generated .* DO NOT EDIT\.[[:space:]]*$|^[[:space:]]*(//|#|\*|/\*|--|<!--)[[:space:]]*@generated([[:space:]]|\(|$)|^[[:space:]]*(//[[:space:]]*)?<auto-generated'
+
 # Should this path be excluded as tracked-but-noisy? `.gitignore` already drops
 # generated/ignored output; this catches the COMMITTED noise it doesn't —
 # vendored trees, minified bundles, migrations, snapshots — that would otherwise
@@ -118,6 +129,7 @@ build_source_inventory() {
             -type f -print0 2>/dev/null | _filter_inventory > "$lst"
     fi
     _apply_gitattr_excludes "$lst"          # author-declared generated/vendored (.gitattributes)
+    _apply_generated_excludes "$lst"        # generated-file markers (#114, opt-in CHECKUP_EXCLUDE_GENERATED)
     [ -n "${CHECKUP_SRC_ROOTS:-}" ] && SOURCE_SCOPE="override:$SOURCE_SCOPE"
     SOURCE_LST="$lst"
     SOURCE_FILE_COUNT=$(tr -cd '\0' < "$lst" | wc -c | tr -d ' ')
@@ -165,6 +177,33 @@ _apply_gitattr_excludes() {
     return 0
 }
 
+# Drop files whose head carries a BANNER-SHAPED generated marker (#114, plan 0002
+# Phase 2) — the corvus lever. OPT-IN via CHECKUP_EXCLUDE_GENERATED (default off)
+# so the regex is field-tested with zero default-behaviour change before any flip
+# to default-on. Rewrites the NUL list at $1 in place (order-preserving) and
+# ENUMERATES the dropped files to "<lst>.generated" (loud, not a silent count —
+# the guard that earns the subtractive design; over-exclusion is the danger).
+# Sets GENERATED_EXCLUDED_COUNT. Runs with cwd == TARGET so the relative paths open.
+_apply_generated_excludes() {
+    local lst="$1"
+    [ -n "${CHECKUP_EXCLUDE_GENERATED:-}" ] && [ -s "$lst" ] || return 0
+    local flagged="$lst.generated"
+    # grep -l short-circuits on the first match per file (the marker is at the head),
+    # so even a mostly-generated tree is cheap; -I skips binaries; LC_ALL=C makes the
+    # match byte-deterministic (#96). xargs streams the list (ARG_MAX-safe, #105).
+    LC_ALL=C xargs -0 grep -lIZ -E "$INV_GENERATED_RE" < "$lst" 2>/dev/null > "$flagged" || true
+    if [ ! -s "$flagged" ]; then rm -f "$flagged"; return 0; fi
+    local p out="$lst.gen"
+    declare -A _gen=()
+    while IFS= read -r -d '' p; do _gen["$p"]=1; done < "$flagged"
+    while IFS= read -r -d '' p; do
+        [ -n "${_gen[$p]:-}" ] || printf '%s\0' "$p"
+    done < "$lst" > "$out"
+    mv "$out" "$lst"
+    GENERATED_EXCLUDED_COUNT="${#_gen[@]}"
+    return 0
+}
+
 # Build the scc keep-set: VCS-tracked files (ALL extensions) minus the exclusions,
 # as a JSON array at $RAW_DIR/scc-keep.json (sets SCC_KEEP_JSON). The scc-based
 # engines filter their --by-file output against this (lib/scc-inventory.sh), so
@@ -183,6 +222,7 @@ build_scc_keepset() {
             -type f -print0 2>/dev/null | _filter_keep > "$lst"
     fi
     _apply_gitattr_excludes "$lst"          # author-declared generated/vendored (.gitattributes)
+    _apply_generated_excludes "$lst"        # generated-file markers (#114, opt-in CHECKUP_EXCLUDE_GENERATED)
     jq -Rs 'split("\u0000") | map(select(length > 0))' < "$lst" > "$SCC_KEEP_JSON" 2>/dev/null \
         || printf '[]' > "$SCC_KEEP_JSON"
     return 0
diff --git a/test/source-inventory.test.sh b/test/source-inventory.test.sh
index c0f0caf..274cf4e 100755
--- a/test/source-inventory.test.sh
+++ b/test/source-inventory.test.sh
@@ -155,6 +155,38 @@ else
     echo "  ⊘ skipped — git not installed"
 fi
 
+echo ""
+echo "generated-marker exclusion: opt-in, banner-shaped, keeps marker-quoting first-party (#114)"
+if command -v git > /dev/null 2>&1; then
+    G="$HOME/.checkup-gen.$$"; rm -rf "$G"; mkdir -p "$G/gen" "$G/src"
+    ( cd "$G"
+      git init -q && git config user.email t@t && git config user.name t
+      printf '// Code generated by protoc-gen-go. DO NOT EDIT.\npackage x\n' > gen/api.pb.go   # Go banner → drop
+      printf '// @generated\nexport const w=1;\n'                            > src/widget.js   # @generated → drop
+      printf '// <auto-generated>\nclass M {}\n'                             > src/Model.cs    # C# designer → drop
+      printf '// normal hand-written\nexport const a=1;\n'                   > src/app.js       # keep
+      printf '// This documents the @generated convention\npackage y\n'      > src/notes.go     # prose → keep
+      printf '# DO NOT EDIT - managed by our own tool\nx=1\n'                > src/migrate.py   # bare DO NOT EDIT → keep
+      git add -A && git commit -qm init >/dev/null 2>&1 )
+    # Opt-in OFF (default): nothing dropped on markers.
+    off=$( cd "$G"; GIT_OK=true; RAW_DIR="$G/raw"; SCAN_ROOTS=(.); build_source_inventory; tr '\0' '\n' < "$SOURCE_LST" | sort | paste -sd',' - )
+    assert_eq "default (opt-in off) keeps everything" \
+        "gen/api.pb.go,src/Model.cs,src/app.js,src/migrate.py,src/notes.go,src/widget.js" "$off"
+    # Opt-in ON: the three banner-shaped generated files drop; the marker-quoting
+    # first-party files (prose, bare DO NOT EDIT) are kept (Morlock M1).
+    on=$( cd "$G"; GIT_OK=true; RAW_DIR="$G/raw"; SCAN_ROOTS=(.); CHECKUP_EXCLUDE_GENERATED=1; build_source_inventory
+          tr '\0' '\n' < "$SOURCE_LST" | sort | paste -sd',' - )
+    assert_eq "opt-in drops banner-shaped generated, keeps marker-quoting first-party" \
+        "src/app.js,src/migrate.py,src/notes.go" "$on"
+    cnt=$( cd "$G"; GIT_OK=true; RAW_DIR="$G/raw"; SCAN_ROOTS=(.); CHECKUP_EXCLUDE_GENERATED=1; build_source_inventory; printf '%s' "$GENERATED_EXCLUDED_COUNT" )
+    assert_eq "GENERATED_EXCLUDED_COUNT set" "3" "$cnt"
+    enum=$( cd "$G"; GIT_OK=true; RAW_DIR="$G/raw"; SCAN_ROOTS=(.); CHECKUP_EXCLUDE_GENERATED=1; build_source_inventory; tr '\0' '\n' < "$RAW_DIR/source-files.lst.generated" | sort | paste -sd',' - )
+    assert_eq "drops enumerated (loud, not silent)" "gen/api.pb.go,src/Model.cs,src/widget.js" "$enum"
+    rm -rf "$G"
+else
+    echo "  ⊘ skipped — git not installed"
+fi
+
 echo ""
 echo "coverage helpers: by-area grouping and exclusion-source label"
 SOURCE_LST="$TMP/cov.lst"