--- title: "Project configuration" description: "Complete reference for rosette.toml project, layer, DRC, DFM, check, and snapshot settings." canonical_url: "https://www.rosette.dev/docs/guides/project-configuration" markdown_url: "https://www.rosette.dev/docs/guides/project-configuration.md" source_url: "https://github.com/PreFab-Photonics/rosette/blob/7b56f8d23880601adc749cdd767ab604d8810051/www/content/docs/guides/project-configuration.mdx" docs_channel: "main" docs_revision: "7b56f8d23880601adc749cdd767ab604d8810051" --- # Project configuration `rosette.toml` is the project configuration file for Rosette. It records project metadata, names GDS layers, and configures verification and snapshot behavior. This page is the canonical reference for its supported sections and keys. ## Config discovery An explicit `config_path` passed to a Python loader or CLI command always wins. Otherwise: * Commands operating on a design search from the design file's directory toward the filesystem root and use the nearest `rosette.toml`. * Direct calls to `load_layer_map`, `load_drc_rules`, `load_dfm_config`, and `load_checks_config` search from the current directory upward. * `rosette update` must run from the project directory containing `rosette.toml`. Rosette recognizes six top-level sections: | Section | Purpose | | ------------- | ----------------------------------------------- | | `[project]` | Project name and template provenance. | | `[layers]` | Named GDS layers and viewer display properties. | | `[drc]` | Per-layer and inter-layer design rules. | | `[dfm]` | Manufacturability prediction settings. | | `[checks]` | Connectivity and bend-radius checks. | | `[snapshots]` | `rosette shot` retention. | Unknown keys produce warnings rather than errors. Valid settings in the same section still load, so warnings can catch typos without breaking existing projects. ## Project `rosette init` writes project metadata used by `rosette update`: ```toml [project] name = "my-chip" template = "generic" ``` | Key | Type | Default | Meaning | | ---------- | ------ | ---------------------- | ---------------------------------------------------------------------------------------------------------------------------- | | `name` | string | Project directory name | Project name substituted into managed template files during `rosette update`. | | `template` | string | `"blank"` | Template whose managed references and agent files `rosette update` refreshes. Built-in values are `"blank"` and `"generic"`. | ## Layers Each child table under `[layers]` assigns a semantic name to one GDS layer/datatype pair: ```toml [layers.silicon] number = 1 datatype = 0 color = "#ff69b4" fill = "solid" opacity = 0.7 description = "Silicon waveguides" ``` | Key | Type | Default | Meaning | | ------------- | ------- | ----------- | -------------------------------------------------------- | | `number` | integer | Required | GDS layer number from 0 through 999. | | `datatype` | integer | `0` | GDS datatype from 0 through 999. | | `color` | string | `"#808080"` | Six-digit hexadecimal viewer color. | | `fill` | string | `"solid"` | `"solid"`, `"hatched"`, `"crosshatched"`, or `"dotted"`. | | `opacity` | number | `0.7` | Viewer opacity from 0.0 through 1.0. | | `description` | string | `""` | Human-readable layer description. | Layer names must map to unique `(number, datatype)` pairs. If `[layers]` is absent or empty, Rosette provides `silicon` as `1/0` and `text` as `10/0`. ### Layer references DRC and DFM settings accept any of these forms: | Form | Example | Meaning | | --------------- | ----------- | ------------------------------------------------- | | Semantic name | `"silicon"` | Resolves through `[layers.silicon]`. Recommended. | | Number/datatype | `"1/0"` | Uses GDS layer 1, datatype 0. | | Number | `"1"` | Shorthand for GDS layer 1, datatype 0. | ## Design rule checking DRC supports global settings, per-layer rules, and typed inter-layer rules. See [Design rule checking](/docs/guides/design-rule-checking) for workflows and result handling. ### Global DRC settings ```toml [drc] warning_margin = 0.01 ``` | Key | Type | Default | Meaning | | ---------------- | --------------- | ------- | ------------------------------------------------------------------------------------------------------------------------------------------ | | `warning_margin` | number | `0` | Absolute margin in design units for downgrading near-threshold length violations to warnings. Values at or below zero disable downgrading. | | `layers` | table | `{}` | Parent table for per-layer rules. | | `rules` | array of tables | `[]` | Inter-layer rules declared with `[[drc.rules]]`. | An absent `[drc]` section loads an empty rule set. ### Per-layer rules ```toml [drc.layers.silicon] min_width = 0.12 min_spacing = 0.13 acute_angle = 60 no_overlap = true ``` Dimensions use design units, normally micrometers. Angles use degrees. | Key | Type | Meaning | | ---------------------- | ---------------- | ----------------------------------------------- | | `min_width` | number | Minimum feature width. | | `max_width` | number | Maximum feature width. | | `min_spacing` | number | Minimum spacing between polygons on this layer. | | `min_area` | number | Minimum polygon area in squared design units. | | `min_edge_length` | number | Minimum polygon edge length. | | `angles` | array of numbers | Allowed edge angles. | | `acute_angle` | number | Minimum convex interior angle. | | `no_overlap` | boolean | Forbid overlapping polygons on this layer. | | `no_self_intersection` | boolean | Forbid self-intersecting polygons. | | `snap_to_grid` | number | Manufacturing grid pitch. | | `density` | table | Sliding-window density constraints. | Density is a nested table: ```toml [drc.layers.silicon.density] min = 0.20 max = 0.80 window = 100.0 step = 50.0 region_layer = "chip_boundary" ``` | Key | Type | Default | Meaning | | -------------- | --------------- | ---------------- | ------------------------------------------------------------------------------------------------- | | `min` | number | None | Minimum fill fraction. At least one of `min` or `max` is required. | | `max` | number | None | Maximum fill fraction. Must be greater than or equal to `min` when both are set. | | `window` | number | Required | Positive square window size in design units. | | `step` | number | Half of `window` | Positive distance between windows. | | `region_layer` | layer reference | None | Marker layer whose union limits the checked region. The design bounding box is used when omitted. | ### Inter-layer rules Every `[[drc.rules]]` entry requires `type`, accepts an optional `name`, and supports only the fields associated with that type. | Type | Required fields | Meaning | | ----------------- | --------------------------------- | ------------------------------------------------------------------------- | | `spacing` | `layer1`, `layer2`, `min_spacing` | Require minimum spacing between two layers. | | `enclosure` | `inner`, `outer`, `min_enclosure` | Require the outer layer to enclose the inner layer by a minimum distance. | | `require_overlap` | `layer1`, `layer2` | Require the two layers to overlap. | | `forbid_overlap` | `layer1`, `layer2` | Forbid overlap between the two layers. | | `not_inside` | `inner`, `outer` | Forbid inner-layer shapes from sitting fully inside the outer layer. | ```toml [[drc.rules]] type = "spacing" layer1 = "p_doping" layer2 = "n_doping" min_spacing = 0.5 name = "PN_SPC" ``` ## Design for manufacturability DFM prediction is disabled when `[dfm]` is absent or empty. Once the section contains settings, `layers` is required and must contain at least one explicit layer reference. ```toml [dfm] resolution = 0.01 padding = 1.0 model = "gaussian" sigma = 0.08 threshold = 0.5 keep_raster = false layers = ["silicon"] max_area_deviation = 0.10 severity = "warning" ``` | Key | Type | Default | Meaning | | -------------------- | ------------------------- | ------------ | ----------------------------------------------------------------------------------------------------------- | | `resolution` | number | `0.01` | Positive raster pixel size in design units. | | `padding` | number | `1.0` | Margin around the cell bounding box in design units. | | `model` | string | `"gaussian"` | Prediction model. Only `"gaussian"` is currently supported. | | `sigma` | number | `0.08` | Non-negative Gaussian blur sigma in design units. | | `threshold` | number | `0.5` | Binarization threshold from 0.0 through 1.0. | | `contour_threshold` | number | `0.5` | Compatibility spelling for `threshold`. If both differ, `threshold` wins and Rosette warns. | | `keep_raster` | boolean | `false` | Retain raster data in prediction results. | | `layers` | array of layer references | Required | Non-empty list of layers to predict. There is no implicit "all layers" mode. | | `max_area_deviation` | number | None | Positive relative area-deviation tolerance. Omit for informational prediction without this violation check. | | `severity` | string | `"error"` | `"error"` or `"warning"` for configured tolerance violations. | | `layer` | table | `{}` | Parent table for per-layer overrides. | Per-layer tables override model or tolerance settings for one layer: ```toml [dfm.layer.silicon] sigma = 0.05 max_area_deviation = 0.05 severity = "warning" ``` | Key | Type | Meaning | | -------------------- | ------ | ------------------------------------------- | | `sigma` | number | Gaussian sigma override. | | `max_area_deviation` | number | Relative area-deviation tolerance override. | | `severity` | string | `"error"` or `"warning"` override. | ## Design checks `[checks]` configures connectivity and route bend-radius checks. If the section or file is absent, the defaults below apply. ```toml [checks] position_tolerance = 0.001 angle_tolerance = 0.1 width_tolerance = 0.000001 check_widths = true min_bend_radius = 5.0 severity = "error" ``` | Key | Type | Default | Meaning | | -------------------- | ------- | ---------- | ------------------------------------------------------------------------------- | | `position_tolerance` | number | `0.001` | Maximum port-center gap in design units for ports to count as connected. | | `angle_tolerance` | number | `0.1` | Maximum angular deviation from anti-parallel, in degrees. | | `width_tolerance` | number | `0.000001` | Maximum absolute connected-port width difference in design units. | | `check_widths` | boolean | `true` | Report width mismatches between connected ports. | | `min_bend_radius` | number | None | Minimum bend radius in design units. Omit to skip bend-radius threshold checks. | | `severity` | string | `"error"` | `"error"` or `"warning"` for configurable violations. | Numeric tolerances must be finite and nonnegative; `angle_tolerance` cannot exceed 180 degrees, and `min_bend_radius` must be positive. Warning-only runs pass while retaining their diagnostics. ## Snapshots `[snapshots]` controls pruning for snapshots written to the default `.rosette/snapshots/` directory: ```toml [snapshots] retain = 50 ``` | Key | Type | Default | Meaning | | -------- | ------- | ------- | ---------------------------------------------------------------------------------- | | `retain` | integer | `20` | Number of newest PNG snapshots to keep. Zero or a negative value disables pruning. | An invalid non-integer value falls back to 20. The `rosette shot --retain` option overrides the config for one invocation. See [Snapshots](/docs/guides/snapshots) for output and pruning details. ## Unsupported historical settings `[build]` and `[project].version` are not part of the schema. Build output is controlled by command options such as `rosette build --output`; package version information belongs to the installed Rosette package rather than a project file.