feat: Implement strict trace continuation

[giortzisg]

Description

Implements the strict_trace_continuation feature for the Sentry Ruby SDK. This controls whether the SDK continues traces from unknown third-party services that happen to be instrumented by Sentry.

Changes

• DSN org_id extraction: Parse org ID from the DSN host (e.g., o123.ingest.sentry.io -> "123") using the ORG_ID_REGEX pattern
• org_id config option: An explicit setting that takes precedence over DSN parsing (useful for self-hosted/Relay setups)
• strict_trace_continuation config option: Boolean, default false. Controls trace continuation behavior
• Baggage propagation: Propagate org_id as sentry-org_id in outgoing baggage (both from PropagationContext and Transaction head baggage)
• Incoming trace validation: Compare incoming sentry-org_id baggage against the SDK's own org ID per the decision matrix

Decision Matrix

Baggage org	SDK org	strict_trace_continuation	Result
1	1	false	Continue
None	1	false	Continue
1	None	false	Continue
None	None	false	Continue
1	2	false	Start new
1	1	true	Continue
None	1	true	Start new
1	None	true	Start new
None	None	true	Continue
1	2	true	Start new

Files Modified

• sentry-ruby/lib/sentry/dsn.rb - org_id extraction from DSN host
• sentry-ruby/lib/sentry/configuration.rb - org_id, strict_trace_continuation, effective_org_id
• sentry-ruby/lib/sentry/propagation_context.rb - should_continue_trace? validation + org_id in head baggage
• sentry-ruby/lib/sentry/transaction.rb - org_id in head baggage
• sentry-ruby/spec/sentry/dsn_spec.rb - Tests for org_id parsing and override
• sentry-ruby/spec/sentry/propagation_context_spec.rb - Tests for full decision matrix

Reference Implementations

• Go: feat: add StrictTraceContinuation option sentry-go#1210
• Python: Add org_id support sentry-python#5166
• Python (follow-up): feat: Implement strict_trace_continuation sentry-python#5178

Closes #2865

🤖 Generated with Claude Code

[dingsdax]

this could be more idiomatic imho 🤔

def self.should_continue_trace?(incoming_baggage)
  return true unless Sentry.initialized?

  configuration   = Sentry.configuration
  sdk_org_id      = configuration.effective_org_id
  baggage_org_id  = incoming_baggage&.items&.fetch("org_id", nil)

  # Always start a new trace if both org IDs are present but don't match
  if sdk_org_id && baggage_org_id && sdk_org_id != baggage_org_id
    return false
  end

  # In non-strict mode, continue unless explicitly rejected above
  return true unless configuration.strict_trace_continuation

  # Strict mode:
  # - continue if both are missing
  # - otherwise require exact match
  return true if sdk_org_id.nil? && baggage_org_id.nil?

  sdk_org_id == baggage_org_id
end