on brain_write(page, fact):
    # EVERY fact gets a citation -- compiled truth AND timeline
    citation = format_citation(source)
    #   format: [Source: {who}, {channel/context}, {date} {time} {tz}]

    # Category-specific formats:
    if source.type == "direct":
        # [Source: User, direct message, 2026-04-07 12:33 PM PT]
    elif source.type == "meeting":
        # [Source: Meeting notes "Team Sync" #12345, 2026-04-03 12:11 PM PT]
    elif source.type == "api_enrichment":
        # [Source: Crustdata LinkedIn enrichment, 2026-04-07 12:35 PM PT]
    elif source.type == "social_media":
        # MUST include full URL -- not just @handle
        # [Source: X/@pedroh96 tweet, product launch, 2026-04-07](https://x.com/pedroh96/status/...)
    elif source.type == "email":
        # [Source: email from Sarah Chen re Q2 board deck, 2026-04-05 2:30 PM PT]
    elif source.type == "workspace":
        # [Source: Slack #engineering, Keith re deploy schedule, 2026-04-06 11:45 AM PT]
    elif source.type == "web":
        # [Source: Happenstance research, 2026-04-07 12:35 PM PT]
    elif source.type == "published":
        # [Source: [Wall Street Journal, 2026-04-05](https://wsj.com/...)]
    elif source.type == "funding":
        # [Source: Captain API funding data, 2026-04-07 2:00 PM PT]

    # Attach citation inline with the fact
    modusbrain put <slug> --content "...fact [Source: ...]..."

    # When sources conflict, note BOTH -- never silently pick one
    if conflicts_exist(fact, existing_page):
        append_to_compiled_truth(
            "Conflict: Source A says X, Source B says Y. "
            "[Source: A] [Source: B]"
        )

# Source hierarchy for conflict resolution (highest authority first):
SOURCE_PRIORITY = [
    "User direct statements",      # 1 -- always wins
    "Primary sources",             # 2 -- meetings, emails, direct conversations
    "Enrichment APIs",             # 3 -- Crustdata, Happenstance, Captain
    "Web search results",          # 4
    "Social media posts",          # 5
]