feat(epistemics): record assertions between observations and beliefs

A statement made to a mind is now three things kept apart: the observation
that it arrived, an append-only assertion (attributed actor, stance,
certainty, modality, negation, reported or quoted speech, hypothetical
status, interpretation confidence and notes), and, only for factual
assertions, one piece of evidence for a proposition belief attributed to
whoever actually stands behind it. Reported speech is attributed to the
person reported and weighed as second-hand; hypotheticals, questions and
imperatives create no belief; expressed doubt counts against; a possibly
sarcastic remark is recorded with low interpretation confidence rather
than guessed at. Interpretation is deterministic code; a model may enrich
the claim list but never sets stance or confidence.

Association no longer treats conversational turns as world events:
hypotheticals, questions, requests and consecutive turns by one speaker
cannot seed causal hypotheses.

Adds internal/epistemics, migration 0018, the assertions API, assertions
on belief pages and in belief detail, a shared end-to-end test harness
(tests/harness), end-to-end tests for eight speech patterns, and updates
the milestone test to the new provenance.

internal/api/assertions.go

@@ -0,0 +1,69 @@
+package api
+
+import (
+	"net/http"
+	"strconv"
+
+	"github.com/andydixon/noema/internal/auth"
+	"github.com/andydixon/noema/internal/epistemics"
+	"github.com/andydixon/noema/pkg/ids"
+)
+
+// assertionRoutes expose who asserted what to a mind, kept apart from what
+// the mind believes.
+func (s *Server) assertionRoutes() {
+	m := s.mux
+	m.Handle("GET /api/v1/minds/{mind}/assertions", require(auth.RoleObserver, s.assertionsList))
+	m.Handle("GET /api/v1/minds/{mind}/assertions/actors", require(auth.RoleObserver, s.assertionActors))
+}
+
+func (s *Server) assertionsList(w http.ResponseWriter, r *http.Request) {
+	m, ok := s.mind(w, r)
+	if !ok {
+		return
+	}
+	q := r.URL.Query()
+	f := epistemics.Filter{AttributedTo: q.Get("actor"), Stance: q.Get("stance"), Limit: intParam(q.Get("limit"), 100)}
+	if b := q.Get("belief"); b != "" {
+		id, err := ids.Parse(b)
+		if err != nil {
+			fail(w, r, ValidationError("bad belief id"))
+			return
+		}
+		f.BeliefID = id
+	}
+	list, err := s.deps.Assertions.List(r.Context(), m.ID, f)
+	if err != nil {
+		fail(w, r, err)
+		return
+	}
+	if list == nil {
+		list = []epistemics.Assertion{}
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"items": list})
+}
+
+func (s *Server) assertionActors(w http.ResponseWriter, r *http.Request) {
+	m, ok := s.mind(w, r)
+	if !ok {
+		return
+	}
+	list, err := s.deps.Assertions.Actors(r.Context(), m.ID)
+	if err != nil {
+		fail(w, r, err)
+		return
+	}
+	if list == nil {
+		list = []epistemics.ActorSummary{}
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"items": list})
+}
+
+// intParam parses a bounded positive integer query value.
+func intParam(v string, def int) int {
+	n, err := strconv.Atoi(v)
+	if err != nil || n <= 0 {
+		return def
+	}
+	return n
+}