> ## Documentation Index
> Fetch the complete documentation index at: https://worldmonitor-spike-bun-package-manager.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# News Credibility Score

> How WorldMonitor scores per-headline source reliability separately from newsworthiness — source tier, propaganda risk, independent corroboration, and the state-media cap.

## Start here

Every headline in WorldMonitor carries two separate numbers, and keeping them
separate is the entire idea.

**Importance** asks: *how much does this matter right now?*
**Credibility** asks: *how much should I trust this source on this story?*

A state-controlled outlet breaking real news about its own government's military
movements is **highly important and poorly credible at the same time**. Most news
tools collapse that into one ranking and force you to choose between missing the
story and trusting the source. WorldMonitor shows you both numbers and lets you
decide.

### What credibility is built from

| Ingredient                    | Weight | The question behind it                                                            |
| ----------------------------- | -----: | --------------------------------------------------------------------------------- |
| **Propaganda risk**           |   0.50 | Does this outlet answer to a government or an interest with a stake in the story? |
| **Source tier**               |   0.30 | What is this outlet's track record?                                               |
| **Independent corroboration** |   0.20 | Is anyone unconnected reporting the same thing?                                   |

Note what is *absent*. Severity, recency, and how dramatic the event is carry no
weight here at all — those belong to importance. Only things that bear on
truthfulness are allowed to move this number.

<Note>
  **State media is capped, not banned.** An outlet under state control cannot reach
  a high credibility score no matter how many others repeat it — because
  repetition inside a controlled media environment is not independent
  corroboration. It stays visible and readable, with an honest label on it.
</Note>

### No human sits in this loop

The pipeline is automated end to end. Quality comes from a curated source-tier
table, a fail-closed propaganda-risk registry, and corroboration counts the
digest already computes. Third-party bias ratings (AllSides, MBFC) are
deliberately **not** applied today.

<Info>
  **For developers.** The field is `credibilityScore` on `NewsItem`, served from
  `GET /api/news/v1/list-feed-digest` (proto
  `worldmonitor.news.v1.NewsItem.credibility_score`).
</Info>

## How it differs from importance

| Score              | Question                                           | Typical high scorer                                 |
| ------------------ | -------------------------------------------------- | --------------------------------------------------- |
| `importanceScore`  | How newsworthy is this right now?                  | A critical RT flash on a diplomacy/flashpoint event |
| `credibilityScore` | How much should I trust this source on this story? | The same story reported by Reuters                  |

A state-controlled outlet can score **high** on importance and **low** on
credibility at the same time. That split is the product, and mixing the two is
the flaw a sophisticated buyer finds first.

## Inputs

Only inputs that bear on truthfulness enter the score. Severity, recency, and
the diplomacy/flashpoint boost stay on `importanceScore`.

| Component                 | Weight | Source                                                 |
| ------------------------- | ------ | ------------------------------------------------------ |
| Propaganda risk           | `0.50` | `shared/source-provenance.ts` `SOURCE_PROPAGANDA_RISK` |
| Source tier               | `0.30` | `shared/source-tiers.json`                             |
| Independent corroboration | `0.20` | Digest story-identity / entity corroboration count     |

Weights sum to `1.0`. The implementation is `shared/news-credibility.js`
(`computeCredibilityScore`). The digest writes the field after classification
and corroboration, alongside — not instead of — `importanceScore`.

## Component Maps

Source tier maps to:

| Tier          | Score | Meaning                            |
| ------------- | ----- | ---------------------------------- |
| `1`           | `100` | Wire / official                    |
| `2`           | `75`  | Major established outlet           |
| `3`           | `50`  | Specialty / regional               |
| `4` (default) | `25`  | Aggregator, blog, or unlisted feed |

Propaganda risk maps to:

| Risk      | Score | Meaning                                                      |
| --------- | ----- | ------------------------------------------------------------ |
| `low`     | `100` | Reviewed independent journalism                              |
| `medium`  | `50`  | State-affiliated or known editorial tilt                     |
| `unknown` | `35`  | Not yet reviewed — fail-closed, never treated as independent |
| `high`    | `12`  | State-controlled media                                       |

Unlisted sources default to `unknown`, not `low`. That fail-closed default is
the same contract as the provenance badges.

Independent corroboration uses the digest's existing corroboration count (the
larger of story-identity cluster size and entity-level corroboration), capped
at five sources, with `20` points per source before the `0.20` weight. This
is the same corroboration signal `importanceScore` already consumes; it is
not a second clustering pass.

## High-Risk Cap

After the weighted sum is rounded and clamped to `0–100`, a source whose
propaganda risk is `high` is capped at `40`.

The cap is the acceptance gate for state media. An RT or TASS item can still
pick up corroboration points when independent outlets also report the event,
but it cannot look like a high-credibility wire. Reuters with no extra
corroboration scores around `80`; RT with none scores in the low `20`s.

## What This Score Is Not

* It is **not** a statement that the underlying event is false. A true event
  reported first by state media still has low *source* credibility until
  independent outlets corroborate it.
* It is **not** AllSides or MBFC. Those ratings are out of scope until a
  dedicated ingest exists.
* It is **not** used to sort the news list. Relevance sort remains
  `importanceScore`, then publication time. Credibility is displayed, not
  substituted for newsworthiness.
* Same-ecosystem inflation remains a known limitation: five Russian state
  desks clustering on one headline still share one high-risk cap, but the
  corroboration count is the digest's existing publisher-family signal, not a
  new independence classifier.

## Surfaces

| Surface                                | Field                                                |
| -------------------------------------- | ---------------------------------------------------- |
| Feed digest API                        | `NewsItem.credibilityScore`                          |
| News list UI                           | `CRED NN` badge on flat items and clustered cards    |
| Insights / MCP `get_news_intelligence` | `topStories[].credibilityScore`                      |
| MCP `get_news_clusters`                | `clusters[].credibilityScore` for the primary outlet |

## Source Files

* Scorer: `shared/news-credibility.js`
* Digest writer: `server/worldmonitor/news/v1/list-feed-digest.ts`
* API contract: `proto/worldmonitor/news/v1/news_item.proto`
* Provenance registry: `shared/source-provenance.ts`
* Tier table: `shared/source-tiers.json`
* News list render: `src/components/news/source-provenance.ts`,
  `src/components/NewsPanel.ts`
* Pipeline sibling: [News Digest and Briefing](/methodology/news-digest-and-briefing)