feat: text-layer grounding (extractor authority, guard rescue tier, verifier oracle + hi-DPI crops)

- backend/text_layer.py: PyMuPDF text-layer extraction, fuzzy evidence
  bbox matching, 300-DPI crop rendering, coverage-gap signal
- extractor (classic + agent): TEXT LAYER block appended at call sites;
  grounding guard gains text-layer rescue tier (grounding=text_layer stamp)
- verifier: {text_layer} oracle excerpt + evidence-located hi-DPI crops
  replacing full-page images (fallback preserved, I2 guard intact)
- coverage gaps: text-bearing pages with zero extraction -> failed-scope
  gap findings (agent) / log-only (classic)
- config knobs: TEXT_LAYER_ENABLED/MIN_CHARS/MAX_CHARS, VERIFY_TEXT_MAX_CHARS,
  VERIFY_HI_DPI_CROPS, VERIFY_CROP_DPI, VERIFY_CROP_MARGIN_PTS
- tests: 22 new (text_layer unit, grounding/render, runner-level flow)
Spec: docs/superpowers/specs/2026-08-12-text-layer-grounding-design.md

backend/pipeline/extractor.py

@@ -64,7 +64,8 @@ def discipline_from_sheet_number(sheet_number: Optional[str]) -> Optional[str]:
     return None
 
 
-def _is_grounded(value: str, source_text: str, graphical_basis: str = "") -> bool:
+def _is_grounded(value: str, source_text: str, graphical_basis: str = "",
+                 page_text: Optional[str] = None) -> bool:
     """
     Keep an object only if its primary value is supported by its source_text,
     OR it is a graphical object (has graphical_basis with no text to quote).
@@ -72,6 +73,9 @@ def _is_grounded(value: str, source_text: str, graphical_basis: str = "") -> boo
     - If graphical_basis is set and source_text is absent, the object is valid.
     - If the value contains digits, every distinct digit-run must appear in
       source_text (catches invented dimensions/counts/elevations).
+    - Rescue tier: when page_text (the deterministic text layer) is given,
+      digit-runs absent from source_text but present in the page text are
+      still grounded - vision quoted imperfectly but the value is real.
     - If the value has no digits, require some alphabetic-token overlap.
     """
     # Graphical objects (no readable text on sheet) are always allowed through.
@@ -85,7 +89,11 @@ def _is_grounded(value: str, source_text: str, graphical_basis: str = "") -> boo
     val_digits = set(_DIGITS_RE.findall(value))
     if val_digits:
         src_digits = set(_DIGITS_RE.findall(source_text))
-        return val_digits.issubset(src_digits)
+        if val_digits.issubset(src_digits):
+            return True
+        if page_text:
+            return val_digits.issubset(set(_DIGITS_RE.findall(page_text)))
+        return False
 
     # No digits: text-based grounding.
     val_norm = re.sub(r"[^a-z0-9]+", " ", value.lower()).strip()
@@ -109,7 +117,24 @@ def _primary_value(obj: Dict) -> str:
             or obj.get("name") or obj.get("tag") or "")
 
 
-def _normalize_sheet(parsed: Dict, page_number: int) -> Dict:
+def _grounding_stamp(value: str, source_text: str,
+                     page_text: Optional[str]) -> Optional[str]:
+    """\"text_layer\" when the object survived only via the text-layer rescue
+    tier (digits absent from source_text but present in the page text)."""
+    if not page_text:
+        return None
+    val_digits = set(_DIGITS_RE.findall(str(value)))
+    if not val_digits:
+        return None
+    if val_digits.issubset(set(_DIGITS_RE.findall(source_text))):
+        return None
+    if val_digits.issubset(set(_DIGITS_RE.findall(page_text))):
+        return "text_layer"
+    return None
+
+
+def _normalize_sheet(parsed: Dict, page_number: int,
+                     page_text: Optional[str] = None) -> Dict:
     """
     Validate + clean one parsed sheet result, attaching page_number and ids.
 
@@ -138,6 +163,7 @@ def _normalize_sheet(parsed: Dict, page_number: int) -> Dict:
     raw_objects = parsed.get("objects") or parsed.get("assertions") or []
     clean: List[Dict] = []
     dropped = 0
+    rescued = 0
 
     for idx, obj in enumerate(raw_objects):
         if not isinstance(obj, dict):
@@ -149,9 +175,13 @@ def _normalize_sheet(parsed: Dict, page_number: int) -> Dict:
         # Derive a primary value for the grounding check
         primary_val = _primary_value(obj)
 
-        if not _is_grounded(primary_val, source_text, graphical_basis):
+        if not _is_grounded(primary_val, source_text, graphical_basis,
+                            page_text=page_text):
             dropped += 1
             continue
+        grounding = _grounding_stamp(primary_val, source_text, page_text)
+        if grounding:
+            rescued += 1
 
         # --- location_key: new schema is richer; map to legacy shape + extras ---
         lk = obj.get("location_key")
@@ -203,10 +233,13 @@ def _normalize_sheet(parsed: Dict, page_number: int) -> Dict:
             "object_attributes": attrs,
             "graphical_basis":   graphical_basis or None,
             "review_uses":       obj.get("review_uses") or [],
+            **({"grounding": grounding} if grounding else {}),
         })
 
-    if dropped:
-        print(f"[Extract] Page {page_number} ({sheet_number}): dropped {dropped} ungrounded object(s)")
+    if dropped or rescued:
+        print(f"[Extract] Page {page_number} ({sheet_number}): "
+              f"dropped {dropped} ungrounded object(s)"
+              + (f", rescued {rescued} via text layer" if rescued else ""))
 
     unresolved = parsed.get("unresolved_items") or []
 
@@ -223,8 +256,23 @@ def _normalize_sheet(parsed: Dict, page_number: int) -> Dict:
     }
 
 
+def _text_layer_block(page: Dict) -> str:
+    """
+    The TEXT LAYER block appended to the extractor instruction at call sites
+    (NOT a template placeholder - render() silently leaves missing keys as
+    literals). Empty string when the page has no usable text layer.
+    """
+    text = (page.get("text_layer") or "").strip()
+    if not text:
+        return ""
+    return ("\n\nTEXT LAYER (authoritative for alphanumeric content — trust it "
+            "over the image for numbers, tags, and note text):\n"
+            + text[:config.TEXT_LAYER_MAX_CHARS])
+
+
 def _extract_one(page: Dict, sheet_hint: str = "") -> Dict:
-    user_text = EXTRACTOR_USER_INSTRUCTION.replace("{sheet_hint}", sheet_hint)
+    user_text = (EXTRACTOR_USER_INSTRUCTION.replace("{sheet_hint}", sheet_hint)
+                 + _text_layer_block(page))
     parsed = call_json(
         system_prompt=EXTRACTOR_SYSTEM_PROMPT,
         user_text=user_text,
@@ -241,7 +289,8 @@ def _extract_one(page: Dict, sheet_hint: str = "") -> Dict:
             "scale": None,
             "assertions": [],
         }
-    return _normalize_sheet(parsed, page["page_number"])
+    return _normalize_sheet(parsed, page["page_number"],
+                            page_text=page.get("text_layer"))
 
 
 def extract_assertions(pages: List[Dict], on_progress=None) -> List[Dict]: