Render Configuration

The [render] section controls how PRISM renders pages using a headless Chromium browser. It includes sub-sections for the browser tab pool, circuit breaker, HTML postprocessing, viewport emulation, and content validation.

TOML Example

[render]
wait_for = "load"
timeout_secs = 10
block_resources = ["font", "image", "media", "stylesheet"]
status_from_meta = false
fail_on_console_errors = false
min_html_size = 512
post_wait_js = "document.querySelector('.lazy')?.classList.remove('hidden')"

[render.pool]
tabs = 8
max_renders_per_tab = 50
queue_max = 100

[render.circuit_breaker]
failure_threshold = 5
recovery_timeout_secs = 30
half_open_max_requests = 1

[render.postprocess]
enabled = true
strip_scripts = true
strip_noscript = true
strip_comments = true
strip_event_handlers = true
strip_hydration_attrs = true
resolve_lazy_images = true

[render.viewport]
enabled = false
mobile_width = 412
mobile_height = 915
desktop_width = 1920
desktop_height = 1080

[render.content_validation]
enabled = true
min_text_length = 100
require_title = true
min_html_bytes = 1024

Top-Level Parameters

Parameter	Type	Default	Description
wait_for	String	"load"	Page readiness signal: load, domcontentloaded, networkidle, or selector:<CSS>
timeout_secs	Integer	10	Maximum seconds to wait for a page render. Must be > 0
block_resources	Array of Strings	["font", "image", "media", "stylesheet"]	Resource types to block during rendering
status_from_meta	Boolean	false	Extract HTTP status from <meta name="render:status_code"> or <meta name="prism:status">
fail_on_console_errors	Boolean	false	Fall back to origin if JS console errors detected and HTML is below min_html_size
min_html_size	Integer	512	Minimum rendered HTML bytes; below this with console errors triggers fallback
post_wait_js	String or null	null	JavaScript to execute after wait_for completes but before HTML extraction

wait_for

Controls when PRISM considers the page "ready" to extract HTML:

• load (default): Waits for the load event. Good for most SPAs.
• domcontentloaded: Fires earlier, before images/stylesheets finish loading. Faster but may miss lazy content.
• networkidle: Waits until there are no more than 2 network connections for 500ms. Most thorough but slowest.
• selector:<CSS>: Waits until a specific CSS selector appears in the DOM. Example: selector:#app-loaded or selector:.content-ready.

status_from_meta

When enabled, PRISM scans rendered HTML for meta tags like:

<meta name="render:status_code" content="404">
<meta name="prism:status" content="404">

This lets SPAs that render 404 pages client-side communicate the correct HTTP status code to crawlers.

post_wait_js

Optional JavaScript executed after the wait_for condition is met but before HTML is extracted. Useful for DOM fixups on SPAs with lazy hydration, such as removing hidden classes that a framework has not yet removed.

Pool Configuration

The [render.pool] sub-section controls the Chromium browser tab pool.

Parameter	Type	Default	Description
tabs	Integer	8	Number of browser tabs to keep open. Must be > 0
max_renders_per_tab	Integer	50	Renders before recycling a tab (prevents memory leaks)
queue_max	Integer	100	Maximum queued render requests before rejecting new ones

Increasing tabs improves concurrent throughput but uses more memory. Each tab consumes roughly 50-100 MB of RAM depending on page complexity.

Circuit Breaker Configuration

The [render.circuit_breaker] sub-section implements the circuit breaker pattern to protect against cascading failures when Chromium is unhealthy.

Parameter	Type	Default	Description
failure_threshold	Integer	5	Consecutive failures before opening the circuit
recovery_timeout_secs	Integer	30	Seconds to wait before attempting recovery (half-open state)
half_open_max_requests	Integer	1	Number of test requests allowed in half-open state

When the circuit is open, all render requests immediately fall back to the origin response instead of waiting for Chromium.

Postprocess Configuration

The [render.postprocess] sub-section controls HTML cleanup applied to rendered output before caching and serving.

Parameter	Type	Default	Description
enabled	Boolean	true	Enable or disable all postprocessing
strip_scripts	Boolean	true	Remove <script> tags from rendered HTML
strip_noscript	Boolean	true	Remove <noscript> tags
strip_comments	Boolean	true	Remove HTML comments
strip_event_handlers	Boolean	true	Remove inline event handlers (onclick, onload, etc.)
strip_hydration_attrs	Boolean	true	Remove framework hydration attributes (data-reactid, ng-*, etc.)
resolve_lazy_images	Boolean	true	Move data-src to src for lazy-loaded images

Postprocessing produces cleaner HTML for search engine crawlers and reduces response size.

Viewport Configuration

The [render.viewport] sub-section enables viewport emulation for mobile-aware rendering.

Parameter	Type	Default	Description
enabled	Boolean	false	Enable viewport-aware rendering
mobile_width	Integer	412	Width in pixels for mobile viewport
mobile_height	Integer	915	Height in pixels for mobile viewport
desktop_width	Integer	1920	Width in pixels for desktop viewport
desktop_height	Integer	1080	Height in pixels for desktop viewport

When enabled, PRISM detects the requesting device type and sets the browser viewport accordingly. This ensures responsive SPAs render the correct layout for mobile vs. desktop crawlers (e.g., Googlebot Mobile).

Content Validation Configuration

The [render.content_validation] sub-section validates rendered output quality before caching and serving.

Parameter	Type	Default	Description
enabled	Boolean	true	Enable content validation
min_text_length	Integer	100	Minimum visible text characters (after stripping HTML tags)
require_title	Boolean	true	Require a non-empty <title> tag in rendered output
min_html_bytes	Integer	1024	Minimum total HTML size in bytes

Content validation catches broken renders (empty pages, error screens) and prevents them from being cached or served to crawlers.

Example Use Cases

React SPA with slow hydration

[render]
wait_for = "selector:#app-ready"
timeout_secs = 15
post_wait_js = "document.querySelectorAll('.skeleton').forEach(el => el.remove())"

[render.pool]
tabs = 12
queue_max = 200

High-traffic site with conservative settings

[render]
wait_for = "load"
timeout_secs = 8
fail_on_console_errors = true
min_html_size = 1024

[render.circuit_breaker]
failure_threshold = 3
recovery_timeout_secs = 60

[render.content_validation]
enabled = true
min_text_length = 200
min_html_bytes = 2048

Minimal postprocessing for debugging

[render.postprocess]
enabled = true
strip_scripts = false
strip_comments = false
strip_hydration_attrs = false