Entity Detection: Run It on Every Message

Goal

Every inbound message gets scanned for original thinking AND entity mentions so the brain grows on every conversation, automatically.

What the User Gets

Without this: the agent answers questions but forgets everything. You mention Alice in a meeting, and next week the agent doesn't know who Alice is.

With this: every person, company, and idea mentioned in conversation gets a brain page. Next time Alice comes up, the agent already has context. The brain compounds.

Implementation

Spawn a lightweight sub-agent on EVERY inbound message. Do NOT wait for it to finish before responding. It runs in parallel.

This pattern is harness-side by design, but gbrain ships help on both ends: the signal-detector skill (skills/signal-detector/) is the bundled version of this detection loop, and gbrain extract runs gbrain's own extraction machinery (entities, facts) over already-synced content.

on_every_message(message_text, source_context):

  // 1. SPAWN ASYNC — don't block the response
  spawn_subagent({
    model: "sonnet-class",     // cheap + fast, not opus
    timeout: 120,              // seconds
    task: build_detection_prompt(message_text, source_context)
  })

  // 2. RESPOND TO USER NORMALLY
  // The sub-agent runs in the background

The Detection Prompt

build_detection_prompt(text, source):
  return `
SIGNAL DETECTION — scan this message for ideas AND entities:

Message: "${text}"
Source: [Source: User, ${source.topic}, ${source.platform}, ${source.timestamp}]

STEP 1 — IDEAS FIRST (highest priority):
Is the user expressing an original thought, observation, thesis, or framework?

If yes:
  - Create or update brain/originals/{slug}.md
  - Use the user's EXACT phrasing (the language IS the insight)
  - "The ambition-to-lifespan ratio has never been more broken" is better
    than "tension between ambition and mortality"
  - Include [Source: ...] citation with full context

If the idea references a world concept: brain/concepts/{slug}.md
If it's a product/business idea: brain/ideas/{slug}.md

STEP 2 — ENTITIES:
Extract all person names, company names, media titles.

For each entity:
  a. Run: gbrain search "{name}"
  b. If page exists AND new info: append timeline entry
     Format: - YYYY-MM-DD | {what happened} [Source: {who}, {context}, {date}]
  c. If no page AND entity is notable: create page with web enrichment
  d. If page is thin (< 5 lines compiled truth): spawn background enrichment

STEP 3 — BACK-LINKING (mandatory):
For every entity mentioned, add a back-link FROM their page TO this source.
An unlinked mention is a broken brain.
Format: - **YYYY-MM-DD** | Referenced in [{page title}]({path}) — {context}

STEP 4 — SYNC:
Run: gbrain sync --no-pull --no-embed

If nothing to capture, reply "No signals detected" and exit.
`

Notability Filtering

Before creating a new entity page, check notability:

is_notable(entity):
  // CREATE a page for:
  - People the user knows or discusses with specificity
  - Companies the user is evaluating, working with, or investing in
  - Media the user mentions with personal reaction
  - Anyone the user has explicitly engaged with

  // DON'T create a page for:
  - Generic references or passing examples
  - Low-engagement accounts who mentioned the user once
  - Pure metaphors ("like the Roman Empire...")
  - One-off encounters with no follow-up

  // If notable AND no page: create FULL page (not a stub)
  // If not notable: skip silently

What Counts as Original Thinking

Capture	Don't Capture
Original observations about how the world works	"ok", "do it", "sure"
Novel connections between disparate things	Pure questions without observations
Frameworks and mental models	Echoing back what the agent said
Pattern recognition ("I keep seeing X in every Y")	Acknowledgments and reactions
Hot takes with reasoning	Routine operational messages
Metaphors that reveal new angles	Requests without embedded insight
Emotional/psychological insights about self or others

Filing Rules

Signal	Destination
User generated the idea	`brain/originals/{slug}.md`
User's synthesis of others' ideas	`brain/originals/` (the synthesis is original)
User's ghostwritten book/essay	`brain/originals/` (note ghostwriter in metadata)
World concept someone else coined	`brain/concepts/{slug}.md`
Product or business idea	`brain/ideas/{slug}.md`
Person mentioned	`brain/people/{slug}.md`
Company mentioned	`brain/companies/{slug}.md`
Media referenced	`brain/media/{type}/{slug}.md`
Article ABOUT the user	`brain/media/writings/{slug}.md`

This table is the single home for the capture/filing taxonomy. Other guides (idea-capture especially) link here rather than carrying their own copy.

The Iron Law of Back-Linking

Every entity mention MUST create a back-link FROM the entity page TO the source. This is not optional.

// When message mentions "Alice" and creates a meeting page:

// 1. Update the meeting page (normal)
brain/meetings/2026-04-10-board-sync.md:
  - Alice presented Q1 numbers

// 2. ALSO update Alice's page (back-link)
brain/people/alice-example.md:
  ## Timeline
  - **2026-04-10** | Presented Q1 numbers at board sync
    [Source: User, board meeting, 2026-04-10]

Without back-links, you can't traverse the graph. "Show me everything related to Alice" only works if Alice's page links back to every mention.

Tricky Spots

Don't block the conversation. Entity detection runs async. The user should see a response immediately, not wait 2 minutes while the sub-agent enriches 5 entity pages.
Sonnet, not Opus. Entity detection is pattern matching, not deep reasoning. Sonnet is 5-10x cheaper and fast enough. Use Opus for the main conversation.
Exact phrasing matters. "Markdown is actually code" is an insight. "Markdown can be used as code" is a summary. Capture the first version.
Don't create stubs. If you create a page, make it good. Run a web search, build out the compiled truth, add context. A stub page with just a name is worse than no page (it gives false confidence).
Dedup before creating. Always gbrain search before creating a page. Variant spellings, nicknames, and company abbreviations cause duplicates. "Alice Example" and "Alice" might be the same person.

How to Verify

Send a message mentioning a person. Say "I had coffee with Sarah Chen from Acme Corp today." Verify: brain/people/sarah-chen.md was created or updated, brain/companies/acme-corp.md was created or updated, both have timeline entries with today's date.
Send a message with an original idea. Say "What if we could distribute software as markdown files that agents execute?" Verify: brain/originals/{slug}.md was created with your exact phrasing.
Check back-links. Open Sarah Chen's page. It should have a timeline entry linking back to today's conversation. Open Acme Corp's page. Same.
Send a boring message. Say "ok sounds good." Verify: nothing was created. The detector should report "No signals detected."
Check for duplicates. Mention "Alice" then later "Alice Example." Verify: one page, not two.

Part of the GBrain Skillpack.

entity detection