Viewport highlighter

Viewport Highlighter

Purpose

Automate viewport segmentation of construction drawing sheets. Each sheet typically contains 1-12+ distinct views (floor plans, sections, elevations, details, schedules). This skill identifies all views, determines their boundaries, extracts metadata (title, detail number, scale, type), and creates viewport highlights — producing the same result as a user manually drawing and labeling each viewport in the UI.

Does NOT: modify existing viewports, delete viewports, or change element data. Only creates new viewport highlights and populates their metadata.

---

Step 0: Verify AgentCM Mode

This skill requires AgentCM. It writes viewport overlays through the AgentCM REST API and has no standalone output path.

Check for .construction/ directory at the project root.

If .construction/ is absent, stop immediately and tell the user:

"viewport-highlighter requires an AgentCM project — .construction/ directory not found. This skill submits viewport overlays through the AgentCM API and cannot operate without it. Open this project in AgentCM first, then re-run."

If .construction/ exists:

• Read .construction/CLAUDE.md for project context
• Read .construction/database.yaml for query_command, project_id, api_url
• Read .construction/index/sheet_index.yaml for sheet inventory
• Sheet images at .construction/rasters/{sheet_number}.png
• OCR data queryable via extracted_items table in PostgreSQL
• Write viewports via REST API

Step 1: User Scopes the Task

User provides sheet scope:

• Specific sheets: "A2.01, A2.02, A5.01"
• By discipline: "all architectural sheets"
• All sheets: "every sheet in the set"

Optional: user can specify which view types to look for (e.g., "only floor plans and sections"). Default: identify ALL views on each sheet.

Before proceeding: Confirm the sheet list and any filters with the user. Show the count of sheets to process.

Step 2: Vision — Identify View Boundaries

For each sheet in scope, rasterize to PNG (if not already available) and examine with vision.

# Rasterize on demand if the pre-rendered PNG is missing
${CLAUDE_SKILL_DIR}/../../bin/construction-python \
  ${CLAUDE_SKILL_DIR}/../../scripts/pdf/rasterize_page.py \
  "{pdf_path}" {page_index} --dpi 200 --output /tmp/{sheet_number}.png

Vision task: Examine the full sheet image. Identify every distinct view (drawing area) on the sheet. For each view, extract:

Field	What to look for	Example
Title	View title bar text (usually centered below the view)	"FIRST FLOOR PLAN"
Detail Number	Number in the detail bubble or title bar	"1", "A2.01", "3/A5"
Scale	Scale annotation near the title bar	1/8" = 1'-0", 1/4" = 1'-0", "NTS"
View Type	Classification of the drawing content	plan, section, elevation, detail, schedule
Bounding Region	Approximate rectangle enclosing the entire view (normalized 0-1)	{x: 0.02, y: 0.05, w: 0.48, h: 0.65}

View boundary detection signals

Use these visual cues to determine where one view ends and another begins:

1. Heavy border lines — thick lines separating drawing areas
2. Title bars — horizontal bars with view name, scale, detail number
3. Detail bubbles — circles or hexagons with detail/sheet reference
4. Whitespace gaps — clear separations between drawing content
5. Grid systems — column/row grids define the extents of a plan view
6. Section cut lines — long dash-dot lines with directional arrows
7. Match lines — indicate where a plan continues on another sheet

View type classification

View Type	extractionScope value	Signals
Floor plan	plan	Grid lines, room names/numbers, dimension strings, north arrow
Enlarged plan	plan	"ENLARGED" in title, larger scale than base plan, room detail
Section	section	Section cut reference (e.g., "SECTION A-A"), vertical layers, material hatching
Elevation	elevation	"ELEVATION" in title, facade view, material callouts, floor lines
Detail	detail	Detail bubble reference, large scale (3"=1'-0"), construction assembly closeup
Schedule	schedule	Tabular grid, column headers, row data (door schedule, finish schedule)
Diagram	other	Riser diagrams, single-line diagrams, flow diagrams

Bounding region estimation from vision

When estimating the bounding region as normalized 0-1 coordinates:

• x = left edge of view content / sheet width (0.0 = left edge)
• y = top edge of view content / sheet height (0.0 = top edge)
• width = view content width / sheet width
• height = view content height / sheet height (include title bar)

Include the title bar and any associated notes/legends within the view. Exclude the sheet title block (typically bottom-right corner). Margins: Add ~1% padding on each side to avoid clipping content.

Multi-view sheet layout patterns

Common construction sheet layouts to expect:

• Single view: One large plan fills most of the sheet
• 2-up vertical: Two views stacked (e.g., floor plan top, reflected ceiling bottom)
• 2-up horizontal: Two views side by side (e.g., two elevations)
• Grid layout: 4-6 details arranged in a 2x3 or 3x2 grid
• Mixed: Large plan on left, 2-3 sections/details stacked on right
• Schedule + details: Schedule table in upper portion, details below

Step 3: OCR Anchor Verification

For each vision-identified view, verify and refine metadata using OCR data.

Title verification

Search for the view title text in extracted_items:

{query_command} -c "SELECT id, text, x_min, y_min, x_max, y_max
  FROM extracted_items
  WHERE sheet_id = '{sheet_id}'
    AND text ILIKE '%{distinctive_title_word}%'
  ORDER BY y_max DESC"

The title bar is typically near the bottom of the view content area. Use the title's y-coordinate to refine the view's bottom boundary.

Scale verification

Search for scale text near the title:

{query_command} -c "SELECT id, text, x_min, y_min, x_max, y_max
  FROM extracted_items
  WHERE sheet_id = '{sheet_id}'
    AND text ILIKE '%SCALE%'
    AND y_min BETWEEN {title_y - 0.02} AND {title_y + 0.02}
    AND x_min BETWEEN {title_x - 0.15} AND {title_x + 0.15}"

Common scale text patterns:

• SCALE: 1/8" = 1'-0"
• 1/4" = 1'-0"
• SCALE: NTS (not to scale)
• 3" = 1'-0"

Detail number verification

Search for detail number in title bar area or detail bubbles:

{query_command} -c "SELECT id, text, x_min, y_min, x_max, y_max
  FROM extracted_items
  WHERE sheet_id = '{sheet_id}'
    AND y_min BETWEEN {title_y - 0.02} AND {title_y + 0.02}
    AND x_min BETWEEN {title_x - 0.10} AND {title_x + 0.10}
    AND text ~ '^[0-9A-Z]'"

Detail number formats: 1, 2, A, A2.01, 3/A5, 1/A5.01.

Step 4: Bounding Region Refinement

Refine vision-estimated boundaries using OCR element positions.

Query all extracted items within and near the estimated viewport area:

{query_command} -c "SELECT x_min, y_min, x_max, y_max
  FROM extracted_items
  WHERE sheet_id = '{sheet_id}'
    AND (x_min + x_max) / 2 BETWEEN {est_x - 0.02} AND {est_x + est_w + 0.02}
    AND (y_min + y_max) / 2 BETWEEN {est_y - 0.02} AND {est_y + est_h + 0.02}"

Use the extremes of contained items + 1% padding to set the final bounds.

Overlap prevention

After refining all viewports on a sheet, check for overlaps:

• If two viewports overlap, shrink the boundary of the one with fewer contained elements at the overlapping edge
• Adjacent viewports should have a gap of 0.5-2% of sheet dimension

Validation checklist

Before creating each viewport, verify:

• x >= 0.0 and x + width <= 1.0
• y >= 0.0 and y + height <= 1.0
• width > 0.02 (at least 2% of sheet width)
• height > 0.02 (at least 2% of sheet height)
• Title is non-empty
• View type is one of: plan, section, elevation, detail, schedule, other
• No significant overlap with other viewports on same sheet

Step 5: Submit Viewports for Review

Submit viewport suggestions

Submit all viewports for a sheet as pending suggestions via the viewport suggestion ingest endpoint. The user reviews and approves them in the Group Review Gallery before they become live viewports.

curl -s --fail-with-body -X POST "{api_url}/projects/{project_id}/viewport-suggestions/ingest" \
  -H "Content-Type: application/json" \
  -d '{
    "sheet_id": "{sheet_id}",
    "viewports": [
      {
        "title": "FIRST FLOOR PLAN",
        "detail_number": "1",
        "scale_text": "1/8\" = 1'"'"'-0\"",
        "extraction_scope": "plan",
        "bounding_region": {"x": 0.02, "y": 0.05, "width": 0.48, "height": 0.65},
        "confidence": 0.85,
        "element_ids": []
      },
      {
        "title": "BUILDING SECTION A-A",
        "detail_number": "A",
        "scale_text": "1/4\" = 1'"'"'-0\"",
        "extraction_scope": "section",
        "bounding_region": {"x": 0.52, "y": 0.05, "width": 0.46, "height": 0.45},
        "confidence": 0.80,
        "element_ids": []
      }
    ]
  }'

Response: Returns suggestion_ids for the created pending cards.

Processing order: Submit all viewports for one sheet in a single POST. The system creates group_suggestions rows with status: pending and proposedType: viewport_highlight. Crop images are generated when the user opens the Group Review Gallery.

Confidence scoring:

• 0.90+ = title, scale, and detail number all OCR-verified
• 0.70–0.89 = vision-identified with partial OCR verification
• 0.50–0.69 = vision-only, no OCR anchors found

Review flow

Viewport suggestions appear in the Group Review Gallery as cards with cropped raster previews. The user can:

• Edit title, detail number, scale text, and view type
• Adjust bounding region (future: via canvas interaction)
• Accept → promotes to a live viewport in graph_views with containment rebuild and crop generation
• Reject → suggestion archived, no viewport created

Title formatting conventions

When setting viewport titles, follow these conventions:

• Use the exact title text from the drawing (preserve case)
• If the title includes the sheet number reference (e.g., "1/A5.01"), put only the detail number portion in detail_number and the full title in title
• Common abbreviations to preserve: "FLR", "CLG", "ELEV", "TYP"

Step 6: Verification & Markup

Sheet markup (REQUIRED for all modes)

Mark up each processed sheet with viewport boundary rectangles to show exactly what was identified.

# Build items JSON with rectangles for each viewport
# Convert normalized 0-1 coordinates to pixel coordinates using image dims

${CLAUDE_SKILL_DIR}/../../bin/construction-python \
  ${CLAUDE_SKILL_DIR}/scripts/markup_viewports.py \
  --base "{sheet_image_path}" \
  --items "{items_json_path}" \
  --output "{output_path}" \
  --color "amber" \
  --label-style "titled"

Items JSON format (pixel coordinates):

[
  {
    "x": 100, "y": 200,
    "width": 4000, "height": 3200,
    "shape": "rect",
    "label": "1 - FIRST FLOOR PLAN (plan)"
  },
  {
    "x": 4200, "y": 200,
    "width": 3800, "height": 1500,
    "shape": "rect",
    "label": "A - BUILDING SECTION (section)"
  }
]

Verification report

After processing all sheets, produce a summary:

VIEWPORT HIGHLIGHTING SUMMARY
==============================
Sheets processed: 12
Total viewports created: 47

Sheet      | Views | Types
-----------|-------|------------------
A2.01      |     3 | plan, section, section
A2.02      |     2 | plan, plan
A5.01      |     8 | detail (x8)
A5.02      |     6 | detail (x4), section (x2)
...

Element containment:
  A2.01 / FIRST FLOOR PLAN:     342 elements
  A2.01 / BUILDING SECTION A:    87 elements
  ...

Vision verification (recommended)

After creating all viewports on a sheet, re-examine the marked-up image to verify:

• All views on the sheet are captured (no missing viewports)
• Bounding regions accurately encompass view content
• No significant overlap between viewports
• Title, detail number, and scale text are correct

If issues are found, PATCH the viewport to correct:

curl -s --fail-with-body -X PATCH "{api_url}/projects/{project_id}/viewports/{viewport_id}" \
  -H "Content-Type: application/json" \
  -d '{"title": "CORRECTED TITLE", "boundingRegion": {...}}'

---

Common Pitfalls

1. Title block is not a viewport. Every sheet has a title block (bottom-right, ~15% of sheet). Do NOT create a viewport for it.

2. Revision blocks are not viewports. Revision history areas (right edge) should be excluded.

3. Key plans are not primary viewports. Small orientation diagrams showing which area of the building is depicted — skip these unless the user specifically requests them.

4. Matchline continuation. When a floor plan spans two sheets (A2.01 and A2.02 split at a matchline), each sheet gets its own viewport — they are separate views even though they show one plan.

5. Schedule views. Tabular schedules (door schedule, finish schedule) ARE viewports. Set extractionScope: "schedule".

6. North arrows and legends. Include these within the parent view's bounding region, not as separate viewports.

7. Overlapping views. Some sheets show plans with section cuts and enlarged areas overlaid. The base plan is the viewport — don't create separate viewports for the section cut lines themselves.

8. Scale = "AS NOTED" or "NTS". Some sheets have multiple scales or no scale. Set scaleText to the literal text found.

---

API Reference

Method	Endpoint	Purpose
POST	/api/projects/{id}/viewport-suggestions/ingest	Primary — submit viewport suggestions for review
GET	/api/projects/{id}/sheets/{sheetId}/viewports	List existing (promoted) viewports
POST	/api/projects/{id}/sheets/{sheetId}/viewports	Direct create (manual/bypass review)
PATCH	/api/projects/{id}/viewports/{viewportId}	Update metadata (title, bounds, scale, scope)
GET	/api/projects/{id}/viewports/{viewportId}/elements	Get contained element IDs + count
GET	/api/projects/{id}/viewports/{viewportId}/crop	Fetch auto-generated raster crop PNG
DELETE	/api/projects/{id}/viewports/{viewportId}	Remove viewport (use only if user requests)

ViewportSuggestionIngestBody (primary endpoint)

{
  "sheet_id": "uuid",
  "viewports": [
    {
      "title": "string (required)",
      "detail_number": "string (optional)",
      "scale_text": "string (optional)",
      "extraction_scope": "plan|section|elevation|detail|schedule|other (optional)",
      "bounding_region": { "x": 0.0, "y": 0.0, "width": 0.5, "height": 0.5 },
      "confidence": 0.85,
      "element_ids": ["optional array of extracted_item IDs within viewport"]
    }
  ]
}

CreateViewportBody (direct create — bypass review)

{
  "boundingRegion": { "x": 0.0, "y": 0.0, "width": 0.5, "height": 0.5 },
  "title": "string (required)",
  "detailNumber": "string (optional)",
  "extractionScope": "plan|section|elevation|detail|schedule|other (optional)"
}

GraphViewport (response)

{
  "id": "uuid",
  "sheetId": "uuid",
  "title": "FIRST FLOOR PLAN",
  "detailNumber": "1",
  "scaleText": "1/8\" = 1'-0\"",
  "boundingRegion": { "x": 0.02, "y": 0.05, "width": 0.48, "height": 0.65 },
  "centroid": [0.26, 0.375],
  "bboxSource": "user",
  "elementCount": 342,
  "extractionScope": "plan",
  "userCreated": true,
  "rasterStorageKey": "{projectId}/viewports/{viewportId}.png",
  "createdAt": "2026-04-06T18:30:00Z",
  "updatedAt": "2026-04-06T18:30:00Z"
}

All coordinates are normalized 0-1. Origin is top-left. Multiply by image pixel dimensions to convert to pixel coordinates for markup.

---

Idempotency

Before submitting viewport suggestions for a sheet, check for existing viewports (already promoted/live):

existing=$(curl -s --fail-with-body "{api_url}/projects/{project_id}/sheets/{sheet_id}/viewports")

If viewports already exist on the sheet:

1. Report them to the user
2. Ask whether to skip the sheet, replace existing viewports, or add alongside
3. If replacing: DELETE each existing viewport first, then submit new suggestions
4. Never silently duplicate viewports

Pending suggestions (not yet reviewed) can be safely re-submitted — the ingest endpoint creates new suggestion rows each time. The user resolves duplicates during review in the Group Review Gallery.

---

Allowed Scripts

Allowed scripts — exhaustive list. Only execute these scripts during this skill:

• ../../scripts/pdf/rasterize_page.py — rasterize a sheet PDF page to PNG for vision
• scripts/markup_viewports.py — overlay viewport boundary rectangles on a sheet image