# GSD Report — kerf-engine — M001

## Summary

kerf-engine is 33% complete across 3 milestones. $15.14 spent. Currently executing M002/S01.

1/3Milestones
3/9Slices
planningPhase
$15.14Cost
17.34MTokens
51m 18sDuration
384Tool calls
15Units
6Remaining
16.0/hrRate
$5.05Cost/slice
45.2kTokens/tool
100.0%Cache hit
M001Scope
33%
Executing M002/S01 — Import & Convert UI (View 1)
ETA: ~22m 31s remaining (6 slices at 16.0/hr)

## Blockers

No blockers or high-risk items found.

## Progress

M001 Kerf Engine — Raster-to-Vector Pipeline & API 3/3
S01 Core Pipeline — Preprocessing + Vectorization high — dependency installation, OpenCV+Potrace+VTracer integration critical
untested
S02 Post-Processing + Output Formats (SVG, DXF, JSON) high — DXF generation quality is hard to validate programmatically S01 critical
provides: postprocess_svg() function for RDP simplification + island detection + node countingprovides: Output generators: generate_dxf(), generate_json(), generate_svg()provides: /engine/simplify endpoint for SVG-to-SVG/DXF/JSON simplificationprovides: output_format routing on /engine/trace (svg, dxf, json)provides: _format_response() pattern for consistent multi-format responsesrequires: Core pipeline: preprocessing + potrace_trace() + vtracer_trace() producing raw SVG output
passed
Decisions

- DXF output as raw bytes with application/dxf content-type and metadata in X-Kerf-Metadata header
- postprocess_svg() replaces regex metadata extraction — full XML path parsing for structured PathInfo objects
- _format_response() shared helper for consistent response shaping across endpoints
- Islands placed on separate ISLANDS layer in DXF for downstream CAM tool compatibility
- Bezier curves linearized during post-processing for RDP simplification and DXF polyline generation

Patterns

- PostProcessResult as the universal intermediate representation consumed by all output generators
- Output generators are pure functions: PostProcessResult → bytes/string, no side effects
- _format_response() pattern for consistent multi-format API responses with metadata

S03 Preset System + Engine Docker Packaging low — presets are config files; Docker packaging is well-understood S02 critical
provides: Preset system with 5 tuned configs and merge-based param resolutionprovides: GET /engine/presets endpointprovides: Docker image kerf-engine:dev with healthcheckprovides: GET /engine/health endpointrequires: Post-processing pipeline and output format generators (SVG, DXF, JSON) consumed by preset-driven trace flow
passed
Decisions

- Preset default is 'sign' — covers the most common use case
- Presets use flat JSON with three sections (preprocessing, vectorization, postprocessing)
- resolve_params merges preset → user_params with user taking precedence
- Custom preset has empty param sections so pipeline defaults apply unless user provides overrides
- Multi-stage Docker build separates build deps from runtime (smaller image, no compiler tools)
- Engine image contains only engine source — enforces Engine/App separation (D001)
- Health endpoint at /engine/health for namespace consistency with other /engine/* routes

Patterns

- Preset-driven pipeline configuration: presets define defaults, user params override
- Multi-stage Docker build pattern for Python+C extension packages (pypotrace)
- Dual health endpoints: /health (root) for simple checks, /engine/health (namespaced) for Docker/orchestration

M002 M002 0/3 critical path
S01 Import & Convert UI (View 1) medium — debounced preview updates, Engine API integration from browser critical
untested
S02 Design Canvas Core (View 2) medium — Konva.js setup, selection handles, undo/redo state management S01 critical
provides: postprocess_svg() function for RDP simplification + island detection + node countingprovides: Output generators: generate_dxf(), generate_json(), generate_svg()provides: /engine/simplify endpoint for SVG-to-SVG/DXF/JSON simplificationprovides: output_format routing on /engine/trace (svg, dxf, json)provides: _format_response() pattern for consistent multi-format responsesrequires: Core pipeline: preprocessing + potrace_trace() + vtracer_trace() producing raw SVG output
passed
Decisions

- DXF output as raw bytes with application/dxf content-type and metadata in X-Kerf-Metadata header
- postprocess_svg() replaces regex metadata extraction — full XML path parsing for structured PathInfo objects
- _format_response() shared helper for consistent response shaping across endpoints
- Islands placed on separate ISLANDS layer in DXF for downstream CAM tool compatibility
- Bezier curves linearized during post-processing for RDP simplification and DXF polyline generation

Patterns

- PostProcessResult as the universal intermediate representation consumed by all output generators
- Output generators are pure functions: PostProcessResult → bytes/string, no side effects
- _format_response() pattern for consistent multi-format API responses with metadata

S03 Text System + Font Loading medium — opentype.js integration, font loading from volume, path extraction accuracy S02 critical
provides: Preset system with 5 tuned configs and merge-based param resolutionprovides: GET /engine/presets endpointprovides: Docker image kerf-engine:dev with healthcheckprovides: GET /engine/health endpointrequires: Post-processing pipeline and output format generators (SVG, DXF, JSON) consumed by preset-driven trace flow
passed
Decisions

- Preset default is 'sign' — covers the most common use case
- Presets use flat JSON with three sections (preprocessing, vectorization, postprocessing)
- resolve_params merges preset → user_params with user taking precedence
- Custom preset has empty param sections so pipeline defaults apply unless user provides overrides
- Multi-stage Docker build separates build deps from runtime (smaller image, no compiler tools)
- Engine image contains only engine source — enforces Engine/App separation (D001)
- Health endpoint at /engine/health for namespace consistency with other /engine/* routes

Patterns

- Preset-driven pipeline configuration: presets define defaults, user params override
- Multi-stage Docker build pattern for Python+C extension packages (pypotrace)
- Dual health endpoints: /health (root) for simple checks, /engine/health (namespaced) for Docker/orchestration

M003 M003 0/3
S01 Export Flow (View 3) + DXF Generation high — DXF scale accuracy and geometry quality critical
untested
S02 Docker Packaging + README low — Docker packaging is well-understood pattern S01 critical
provides: postprocess_svg() function for RDP simplification + island detection + node countingprovides: Output generators: generate_dxf(), generate_json(), generate_svg()provides: /engine/simplify endpoint for SVG-to-SVG/DXF/JSON simplificationprovides: output_format routing on /engine/trace (svg, dxf, json)provides: _format_response() pattern for consistent multi-format responsesrequires: Core pipeline: preprocessing + potrace_trace() + vtracer_trace() producing raw SVG output
passed
Decisions

- DXF output as raw bytes with application/dxf content-type and metadata in X-Kerf-Metadata header
- postprocess_svg() replaces regex metadata extraction — full XML path parsing for structured PathInfo objects
- _format_response() shared helper for consistent response shaping across endpoints
- Islands placed on separate ISLANDS layer in DXF for downstream CAM tool compatibility
- Bezier curves linearized during post-processing for RDP simplification and DXF polyline generation

Patterns

- PostProcessResult as the universal intermediate representation consumed by all output generators
- Output generators are pure functions: PostProcessResult → bytes/string, no side effects
- _format_response() pattern for consistent multi-format API responses with metadata

S03 Embed Mode medium — Shadow DOM + Konva.js + font loading interactions S02 critical
provides: Preset system with 5 tuned configs and merge-based param resolutionprovides: GET /engine/presets endpointprovides: Docker image kerf-engine:dev with healthcheckprovides: GET /engine/health endpointrequires: Post-processing pipeline and output format generators (SVG, DXF, JSON) consumed by preset-driven trace flow
passed
Decisions

- Preset default is 'sign' — covers the most common use case
- Presets use flat JSON with three sections (preprocessing, vectorization, postprocessing)
- resolve_params merges preset → user_params with user taking precedence
- Custom preset has empty param sections so pipeline defaults apply unless user provides overrides
- Multi-stage Docker build separates build deps from runtime (smaller image, no compiler tools)
- Engine image contains only engine source — enforces Engine/App separation (D001)
- Health endpoint at /engine/health for namespace consistency with other /engine/* routes

Patterns

- Preset-driven pipeline configuration: presets define defaults, user params override
- Multi-stage Docker build pattern for Python+C extension packages (pypotrace)
- Dual health endpoints: /health (root) for simple checks, /engine/health (namespaced) for Docker/orchestration

## Timeline

# | Type | ID | Model | Started | Duration | Cost | Tokens | Tools | Tier | Routed | Trunc | CHF
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
1 | execute-task | M001/S01/T01 | opus-4-6 | Mar 26, 2026, 04:00 AM | 6m 19s | $1.14 | 1.31M | 39 |  |  |  |
2 | execute-task | M001/S01/T02 | opus-4-6 | Mar 26, 2026, 04:07 AM | 3m 41s | $0.976 | 1.03M | 30 |  |  |  |
3 | execute-task | M001/S01/T03 | opus-4-6 | Mar 26, 2026, 04:11 AM | 3m 59s | $1.12 | 1.29M | 34 |  |  |  |
4 | execute-task | M001/S01/T04 | opus-4-6 | Mar 26, 2026, 04:15 AM | 3m 29s | $0.0000 | 0 | 0 |  |  |  |
5 | execute-task | M001/S01/T05 | opus-4-6 | Mar 26, 2026, 04:18 AM | 4m 8s | $1.37 | 1.35M | 40 |  |  |  |
6 | complete-slice | M001/S01 | opus-4-6 | Mar 26, 2026, 04:22 AM | 3m 19s | $0.734 | 655.6k | 21 |  |  |  |
7 | complete-slice | M001/S01 | opus-4-6 | Mar 26, 2026, 04:25 AM | 2m 4s | $0.796 | 881.5k | 30 |  |  |  |
8 | execute-task | M001/S02/T01 | opus-4-6 | Mar 26, 2026, 04:28 AM | 4m 27s | $1.42 | 1.43M | 29 |  |  |  |
9 | execute-task | M001/S02/T03 | opus-4-6 | Mar 26, 2026, 04:37 AM | 2m 33s | $1.12 | 833.4k | 20 |  |  |  |
10 | complete-slice | M001/S02 | opus-4-6 | Mar 26, 2026, 04:39 AM | 2m 8s | $0.572 | 626.3k | 17 |  |  |  |
11 | execute-task | M001/S03/T01 | opus-4-6 | Mar 26, 2026, 04:42 AM | 3m 51s | $1.44 | 1.64M | 31 |  |  |  |
12 | execute-task | M001/S03/T02 | opus-4-6 | Mar 26, 2026, 04:45 AM | 3m 45s | $1.52 | 2.14M | 35 |  |  |  |
13 | complete-slice | M001/S03 | opus-4-6 | Mar 26, 2026, 04:49 AM | 2m 25s | $0.682 | 870.9k | 20 |  |  |  |
14 | validate-milestone | M001 | opus-4-6 | Mar 26, 2026, 04:52 AM | 2m 30s | $1.29 | 1.96M | 16 |  |  |  |
15 | complete-milestone | M001 | opus-4-6 | Mar 26, 2026, 04:54 AM | 2m 33s | $0.946 | 1.33M | 22 |  |  |  |

## Dependencies

### M001: Kerf Engine — Raster-to-Vector Pipeline & API

done active pending parked

### M002: M002

done active pending parked

### M003: M003

done active pending parked

## Metrics

$15.14Total cost
17.34MTotal tokens
1.2kInput
118.9kOutput
16.60MCache read
616.8kCache write
51m 18sDuration
15Units
384Tool calls
0Truncations

### Token breakdown

Input: 1.2k (0.0%)Output: 118.9k (0.7%)Cache read: 16.60M (95.8%)Cache write: 616.8k (3.6%)

### Cost over time

### Cost by phase

execution
$12.35
11 units
completion
$2.79
4 units

### Tokens by phase

execution
14.31M
$12.35
completion
3.03M
$2.79

### Cost by slice

M001
$2.23
2 units
M001/S01
$6.14
7 units
M001/S02
$3.11
3 units
M001/S03
$3.65
3 units

### Cost by model

opus-4-6
$15.14
15 units

### Duration by slice

M001
5m 3s
$2.23
M001/S01
27m 2s
$6.14
M001/S02
9m 9s
$3.11
M001/S03
10m 2s
$3.65

### Slice timeline

## Health

Token profile | standard
Truncation rate | 0.0% per unit (0 total)
Continue-here rate | 0.0% per unit (0 total)
Tool calls | 384
Messages | 145 assistant / 3 user

### Tier breakdown

Tier | Units | Cost | Tokens
--- | --- | --- | ---
unknown | 15 | $15.14 | 17.34M

## Changelog 3

M001/S03 Preset System + Engine Docker Packaging Mar 26, 2026, 04:52 AM

Shipped 5 pipeline presets (sign, patch, stencil, detailed, custom) with merge-based param resolution, GET /engine/presets endpoint, and a multi-stage Docker image with healthcheck that runs the engine standalone.

Decisions

- Preset default is 'sign' — covers the most common use case
- Presets use flat JSON with three sections (preprocessing, vectorization, postprocessing)
- resolve_params merges preset → user_params with user taking precedence
- Custom preset has empty param sections so pipeline defaults apply unless user provides overrides
- Multi-stage Docker build separates build deps from runtime (smaller image, no compiler tools)
- Engine image contains only engine source — enforces Engine/App separation (D001)
- Health endpoint at /engine/health for namespace consistency with other /engine/* routes

10 files modified

- `engine/presets/sign.json` — Sign preset — aggressive simplification for signage vectorization
- `engine/presets/patch.json` — Patch preset — smooth curves with auto-close for embroidery
- `engine/presets/stencil.json` — Stencil preset — heavy simplification with fixed threshold
- `engine/presets/detailed.json` — Detailed preset — max fidelity for illustrations
- `engine/presets/custom.json` — Custom preset — empty defaults, user controls everything
- `engine/presets/loader.py` — Preset loader with caching, listing, and param merge resolution
- `engine/api/routes.py` — Added GET /engine/presets, GET /engine/health, wired preset into /engine/trace
- `engine/tests/test_presets.py` — 28 tests covering loader, resolution, endpoint, integration, cross-preset differentiation
- `docker/Dockerfile.engine` — Multi-stage Dockerfile: builder compiles pypotrace, runtime uses slim image with engine source only
- `.dockerignore` — Excludes .git, .venv, __pycache__, .gsd, node_modules from Docker build context

M001/S02 Post-Processing + Output Formats (SVG, DXF, JSON) Mar 26, 2026, 04:41 AM

Full post-processing pipeline (RDP simplification, island detection, open path repair) with three output format generators (SVG, DXF, JSON) and /engine/simplify endpoint — 169 tests passing.

Decisions

- DXF output as raw bytes with application/dxf content-type and metadata in X-Kerf-Metadata header
- postprocess_svg() replaces regex metadata extraction — full XML path parsing for structured PathInfo objects
- _format_response() shared helper for consistent response shaping across endpoints
- Islands placed on separate ISLANDS layer in DXF for downstream CAM tool compatibility
- Bezier curves linearized during post-processing for RDP simplification and DXF polyline generation

9 files modified

- `engine/pipeline/postprocess.py` — New: Post-processing module with RDP simplification, island detection, open path repair, SVG path parsing (414 lines)
- `engine/output/__init__.py` — New: Package init exporting generate_dxf, generate_json, generate_svg
- `engine/output/dxf.py` — New: AC1015 DXF generator using ezdxf — LWPOLYLINE entities with island layer separation (66 lines)
- `engine/output/json_output.py` — New: JSON output generator with path commands and properties (76 lines)
- `engine/output/svg.py` — New: SVG output generator returning simplified SVG from PostProcessResult (22 lines)
- `engine/api/routes.py` — Rewritten: integrated postprocess_svg(), output_format routing, /engine/simplify endpoint, _format_response() helper (175 lines)
- `engine/tests/test_postprocess.py` — New: Tests for RDP, island detection, open paths, SVG parsing, node counting (375 lines)
- `engine/tests/test_output.py` — New: Tests for DXF structure, JSON structure, SVG output, round-trip consistency (274 lines)
- `engine/tests/test_api.py` — Rewritten: 35 integration tests for /engine/trace and /engine/simplify across all format combinations (515 lines)

M001/S01 Core Pipeline — Preprocessing + Vectorization Mar 26, 2026, 04:30 AM

## Knowledge 16

### Rules 1

ID | Scope | Rule
--- | --- | ---
# | Scope | Rule

### Patterns 6

ID | Pattern
--- | ---
# | Pattern
P001 | Test images generated programmatically via numpy
P002 | Tests must use .venv/bin/python -m pytest
P003 | PostProcessResult is the universal intermediate representation
P004 | _format_response() for consistent multi-format API responses
P005 | Preset-driven pipeline: resolve_params() merges preset → user

### Lessons 9

ID | Lesson
--- | ---
# | What Happened
L001 | pypotrace fails to build from pip
L002 | VTracer Python bindings work directly — no subprocess needed
L003 | pypotrace Bitmap requires uint32 data
L004 | ezdxf emits pyparsing deprecation warnings in tests
L005 | DXF output format needs binary response, not JSON envelope
L006 | postprocess_svg() fully parses SVG paths into coordinates
L007 | Docker build context must be project root, not engine/
L008 | Engine container has dual health endpoints

## Captures

No captures recorded.

## Artifacts

### Missing changelogs 6

Milestone | Slice | Title
--- | --- | ---
M002 | S01 | Import & Convert UI (View 1)
M002 | S02 | Design Canvas Core (View 2)
M002 | S03 | Text System + Font Loading
M003 | S01 | Export Flow (View 3) + DXF Generation
M003 | S02 | Docker Packaging + README
and 1 more

### Recently completed 3

Milestone | Slice | Title | Completed
--- | --- | --- | ---
M001 | S03 | Preset System + Engine Docker Packaging | Mar 26, 2026, 04:52 AM
M001 | S02 | Post-Processing + Output Formats (SVG, DXF, JSON) | Mar 26, 2026, 04:41 AM
M001 | S01 | Core Pipeline — Preprocessing + Vectorization | Mar 26, 2026, 04:30 AM

## Planning

ID | Milestone | State | Context | Draft | Updated
--- | --- | --- | --- | --- | ---
M001 | Kerf Engine — Raster-to-Vector Pipeline & API | undiscussed |  |  |
M002 | M002 | undiscussed |  |  |
M003 | M003 | undiscussed |  |  |