Site Rules & Auto-Capture

Site Rules

Site Rules control which websites Context Bro auto-captures and how it captures them. Each rule defines a group of domains with its own template, endpoints, capture mode, and dedup settings.

Manual sharing (popup, shortcut, context menu) works on any domain regardless of Site Rules.

Creating a Rule

1. Go to Settings → Sites
2. Enter a name (e.g. “SNS”, “Dev”, “News”) and click Add
3. Add domain patterns, select a template, and choose endpoints

Domain Patterns

Each rule contains one or more domain patterns (one per line):

Pattern	Matches
github.com	Exact domain
*.github.com	All subdomains (gist.github.com, docs.github.com, etc.)
news.ycombinator.com	Exact subdomain

Presets

Click a preset button to quickly create a rule with a curated group of domains:

Preset	Domains
Dev	github.com, stackoverflow.com, developer.mozilla.org, etc.
News	reuters.com, bbc.com, cnn.com, nytimes.com, etc.
Social	reddit.com, twitter.com, mastodon.social, etc.
Streaming	twitch.tv, youtube.com

Per-Rule Template & Endpoints

Each rule can bind to a specific template and one or more endpoints. When auto-capture triggers for that rule, it uses the bound template and sends to the selected endpoints.

Auto-Capture

Enable the Auto-capture toggle on a rule to have Context Bro automatically extract and send page content. Choose between two capture modes:

When Focused (Focused Mode)

Best for pages you’re actively reading — articles, feeds, dashboards.

Behavior	Description
Trigger	You navigate to or focus a tab matching the rule
Dwell	Waits 10 seconds to ensure the page has loaded
Capture	Extracts content once after dwell
Refetch	Optionally re-extracts at a configurable interval (see below)
Stops	When you switch away from the tab or close it

This mode is event-driven — it only runs while you’re actively viewing a matching page.

While Tab Open (Any-Tab Mode)

Best for background monitoring — keeping tabs open that you want periodically captured.

Behavior	Description
Trigger	Chrome Alarm fires at the configured interval
Scope	All open tabs matching the rule’s patterns
Interval	Configurable (minutes or hours)
Capture	Extracts content from every matching tab each cycle

This mode uses the Chrome Alarms API and runs even when the tabs are in the background.

Refetch

Refetch extends focused mode for slowly-changing pages — feeds (HN, Reddit, Twitter), dashboards, monitoring pages, or any content that updates over minutes or hours.

Without refetch, focused mode captures once after the 10-second dwell and stops. With refetch enabled, it continues re-extracting at your configured interval while you stay on the page.

Configuration

Refetch controls appear when a rule has Auto-capture enabled and When focused mode selected:

⊙ Auto-capture  [When focused ▾]
  ☑ Refetch   [30] [sec ▾]
  ☑ Dedup     [15] [min ▾]

Setting	Range	Default
Refetch interval	10 seconds – 1 hour	60 seconds

How Refetch Works

1. You focus a tab matching a focused-mode rule
2. After 10s dwell, initial content is extracted and sent
3. A setInterval timer starts at your configured refetch interval
4. Each tick re-extracts the page content
5. Dedup checks if content has actually changed before sending
6. Timer stops when you switch away, navigate, or close the tab

Refetch + Dedup Interaction

Refetch and dedup work together to minimize unnecessary API calls:

Scenario	Result
Page unchanged, within dedup window	Skip — no API call
Page content changed	Send — new content detected
Dedup window expired (even if same content)	Send — acts as a periodic heartbeat

Deduplication

Each rule has its own dedup toggle and configurable window. When enabled, Context Bro computes a SHA-256 hash of the extracted content. If the content hasn’t changed since the last send within the dedup window, it skips the send.

Setting	Range	Default
Dedup window	Seconds, minutes, or hours	15 minutes

Hashes are stored locally in chrome.storage.local. They are cleared when you clear extension data or uninstall.