diff --git a/internal/status/field_conformance.go b/internal/status/field_conformance.go
new file mode 100644
index 00000000..9cda50bd
--- /dev/null
+++ b/internal/status/field_conformance.go
@@ -0,0 +1,166 @@
+// ABOUTME: Schema-driven per-field conformance — drives type/pattern/enum checks
+// ABOUTME: from the embedded entity.mdschema.yml at the field's declared severity.
+package status
+
+import (
+	"fmt"
+	"regexp"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	spacedock "github.com/spacedock-dev/spacedock"
+	"gopkg.in/yaml.v3"
+)
+
+// schemaField is one entry of the entity mdschema's frontmatter.fields map. Only
+// the keys the field-conformance loop reads are surfaced; unknown keys (semantics,
+// coerce_*, etc.) are ignored by yaml.v3.
+type schemaField struct {
+	Type            string   `yaml:"type"`
+	Pattern         string   `yaml:"pattern"`
+	Conventional    []string `yaml:"conventional"`
+	InvalidSeverity string   `yaml:"invalid_severity"`
+	UnknownSeverity string   `yaml:"unknown_severity"`
+}
+
+// entitySchema is the parsed entity mdschema's field declarations — the SSOT the
+// validator drives per-field checks from.
+type entitySchema struct {
+	fields map[string]schemaField
+}
+
+var (
+	loadedSchema     *entitySchema
+	loadedSchemaOnce sync.Once
+)
+
+// loadEntitySchema parses the embedded entity.mdschema.yml once and returns its
+// field declarations. The schema is JSON (a YAML subset), so yaml.v3 parses it
+// directly. A parse failure yields an empty field set — field conformance is a
+// warn-tier advisory and must never block the binary; a corrupt embedded schema
+// is a build-time problem the schema-driven test (AC-4) catches.
+func loadEntitySchema() *entitySchema {
+	loadedSchemaOnce.Do(func() {
+		var doc struct {
+			Frontmatter struct {
+				Fields map[string]schemaField `yaml:"fields"`
+			} `yaml:"frontmatter"`
+		}
+		s := &entitySchema{fields: map[string]schemaField{}}
+		if err := yaml.Unmarshal(spacedock.EntityMDSchema, &doc); err == nil {
+			s.fields = doc.Frontmatter.Fields
+		}
+		loadedSchema = s
+	})
+	return loadedSchema
+}
+
+// isoLayouts are the timestamp shapes the spacedock writer emits (second and
+// microsecond precision, UTC Z). A value matching any layout is a valid
+// iso8601; the date-only RFC3339 prefix is accepted for fields the FO may set
+// by hand.
+var isoLayouts = []string{
+	time.RFC3339,
+	time.RFC3339Nano,
+	"2006-01-02T15:04:05.000000Z",
+	"2006-01-02",
+}
+
+// isISO8601 reports whether s parses as one of the accepted ISO-8601 layouts.
+func isISO8601(s string) bool {
+	for _, layout := range isoLayouts {
+		if _, err := time.Parse(layout, s); err == nil {
+			return true
+		}
+	}
+	return false
+}
+
+// fieldConformanceWarnings returns warn-tier diagnostics for every active +
+// archived entity whose frontmatter violates a schema field's declared
+// pattern / conventional enum / type, at the field's declared severity. Only
+// fields whose severity is `warn` are surfaced here (no schema field is `error`
+// today; an `error`-severity field would route through the structural-error path
+// instead). Each line names the field and the violated rule plus the entity
+// evidence so the FO can locate the entity.
+func fieldConformanceWarnings(entities []*entity, workflowDir string) []string {
+	schema := loadEntitySchema()
+	var warns []string
+	for _, e := range entities {
+		for name, spec := range schema.fields {
+			if !isWarnSeverity(spec) {
+				continue
+			}
+			value, present := e.fields[name]
+			if !present || value == "" {
+				continue
+			}
+			problem := fieldViolation(name, spec, value)
+			if problem == "" {
+				continue
+			}
+			warns = append(warns, entityEvidenceLine("Warning", e, workflowDir, problem, e.displayID))
+		}
+	}
+	return warns
+}
+
+// isWarnSeverity reports whether a schema field carries a `warn` severity for
+// its conformance check (either invalid_severity or unknown_severity). Fields
+// with a pattern/conventional/type check but no explicit severity default to
+// warn — the schema marks every per-field check warn today, and a field-level
+// conformance gap must never harden into an exit-1 gate without an explicit
+// `error` severity in the schema.
+func isWarnSeverity(spec schemaField) bool {
+	switch spec.InvalidSeverity {
+	case "warn":
+		return true
+	case "error":
+		return false
+	}
+	if spec.UnknownSeverity == "error" {
+		return false
+	}
+	// No explicit invalid_severity: a checkable field (pattern/enum/type) with no
+	// declared severity is advisory (warn). Fields with nothing to check are
+	// skipped by fieldViolation returning "".
+	return spec.Pattern != "" || len(spec.Conventional) > 0 || spec.Type == "iso8601" || spec.Type == "numeric_string"
+}
+
+// fieldViolation returns a human-readable problem string when value violates the
+// field's schema-declared rule, or "" when it conforms / has nothing to check.
+// The rule (pattern, enum, type) is read from the schema spec — never a Go
+// literal — so editing the schema changes what is enforced.
+func fieldViolation(name string, spec schemaField, value string) string {
+	if spec.Pattern != "" {
+		re, err := regexp.Compile(spec.Pattern)
+		if err != nil {
+			return ""
+		}
+		if !re.MatchString(value) {
+			return fmt.Sprintf("field '%s' value %q does not match pattern %s", name, value, spec.Pattern)
+		}
+		return ""
+	}
+	if len(spec.Conventional) > 0 {
+		for _, allowed := range spec.Conventional {
+			if value == allowed {
+				return ""
+			}
+		}
+		return fmt.Sprintf("field '%s' value %q is not one of [%s]", name, value, strings.Join(spec.Conventional, " "))
+	}
+	switch spec.Type {
+	case "numeric_string":
+		if _, err := strconv.ParseFloat(value, 64); err != nil {
+			return fmt.Sprintf("field '%s' value %q is not numeric", name, value)
+		}
+	case "iso8601":
+		if !isISO8601(value) {
+			return fmt.Sprintf("field '%s' value %q is not a valid ISO-8601 timestamp", name, value)
+		}
+	}
+	return ""
+}
diff --git a/internal/status/field_conformance_test.go b/internal/status/field_conformance_test.go
new file mode 100644
index 00000000..7d7ad782
--- /dev/null
+++ b/internal/status/field_conformance_test.go
@@ -0,0 +1,164 @@
+// ABOUTME: Schema-driven field-conformance tests — warn-tier field violations
+// ABOUTME: surface on stderr, exit 0, never gate reads; schema bytes are the source.
+package status
+
+import (
+	"strings"
+	"testing"
+
+	spacedock "github.com/spacedock-dev/spacedock"
+	"gopkg.in/yaml.v3"
+)
+
+// entField builds a sequential-style entity with an extra frontmatter line so a
+// single bad field can be planted while id/status stay clean.
+func entField(id, status, extraKey, extraVal string) string {
+	fm := "---\nid: " + id + "\ntitle: T\nstatus: " + status + "\nscore: \"0.5\"\nsource: x\n"
+	if extraKey != "" {
+		fm += extraKey + ": " + extraVal + "\n"
+	}
+	return fm + "---\n# T\n"
+}
+
+// TestFieldConformanceWarnsSurface locks AC-1: each per-field schema violation
+// the entity schema declares produces a field-named diagnostic on stderr under
+// `--validate`. The bad value lives in the fixture; the rule is the schema's.
+func TestFieldConformanceWarnsSurface(t *testing.T) {
+	env := pinnedEnv(t)
+	cases := []struct {
+		name      string
+		files     map[string]string
+		wantField string // the field name the diagnostic must mention
+	}{
+		{
+			name:      "mod-block-no-colon",
+			files:     map[string]string{"a.md": entField(`"001"`, "backlog", "mod-block", "noColonHere")},
+			wantField: "mod-block",
+		},
+		{
+			name:      "verdict-out-of-enum",
+			files:     map[string]string{"a.md": entField(`"001"`, "backlog", "verdict", "MAYBE")},
+			wantField: "verdict",
+		},
+		{
+			name:      "score-not-numeric",
+			files:     map[string]string{"a.md": entField(`"001"`, "backlog", "score", "notanumber")},
+			wantField: "score",
+		},
+		{
+			name:      "started-malformed-iso",
+			files:     map[string]string{"a.md": entField(`"001"`, "backlog", "started", "not-a-date")},
+			wantField: "started",
+		},
+	}
+	for _, tc := range cases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			root := validationFixture(t, seqREADME, tc.files)
+			_, nErr, nCode := runNative(t, root, env, "--workflow-dir", root, "--validate")
+			if nCode != 0 {
+				t.Fatalf("warn-only fixture must exit 0, got %d (stderr=%q)", nCode, nErr)
+			}
+			// The diagnostic must carry the Warning: prefix bound to the field —
+			// a field-conformance finding is advisory, not a gating Error:. This
+			// pins the warn-vs-error signal the FO reads; flipping the line to
+			// Error: must red this assertion.
+			wantLine := "Warning: field '" + tc.wantField
+			if !strings.Contains(nErr, wantLine) {
+				t.Fatalf("stderr missing warn line %q, got %q", wantLine, nErr)
+			}
+			if strings.Contains(nErr, "Error: field '"+tc.wantField) {
+				t.Fatalf("field-conformance finding misreported as Error: (must be Warning:), got %q", nErr)
+			}
+		})
+	}
+}
+
+// TestFieldConformanceWarnsDoNotGateExit locks AC-2: a warn-only workflow exits
+// 0 with non-empty warning stderr; a structural error (dup id) still exits 1.
+func TestFieldConformanceWarnsDoNotGateExit(t *testing.T) {
+	env := pinnedEnv(t)
+
+	t.Run("warn-only-exits-0", func(t *testing.T) {
+		files := map[string]string{
+			"a.md": entField(`"001"`, "backlog", "verdict", "MAYBE"),
+			"b.md": entField(`"002"`, "done", "mod-block", "noColon"),
+		}
+		root := validationFixture(t, seqREADME, files)
+		nOut, nErr, nCode := runNative(t, root, env, "--workflow-dir", root, "--validate")
+		if nCode != 0 {
+			t.Fatalf("warn-only --validate must exit 0, got %d", nCode)
+		}
+		if strings.TrimSpace(nErr) == "" {
+			t.Fatalf("warn-only --validate must print warnings to stderr, got empty")
+		}
+		if strings.TrimSpace(nOut) != "VALID" {
+			t.Fatalf("warn-only --validate stdout must stay VALID, got %q", nOut)
+		}
+	})
+
+	t.Run("structural-error-exits-1", func(t *testing.T) {
+		files := map[string]string{
+			"a.md": entField(`"001"`, "backlog", "verdict", "MAYBE"),
+			"b.md": entField(`"001"`, "done", "", ""), // dup id == structural error
+		}
+		root := validationFixture(t, seqREADME, files)
+		_, _, nCode := runNative(t, root, env, "--workflow-dir", root, "--validate")
+		if nCode != 1 {
+			t.Fatalf("structural error (dup id) must exit 1, got %d", nCode)
+		}
+	})
+}
+
+// TestFieldConformanceWarnsDoNotGateReads locks AC-3: a warn-tier field
+// violation does not gate the default-table read path — the FO is never locked
+// out by a field warning. Mirrors TestNativeValidationGatesReads inverted.
+func TestFieldConformanceWarnsDoNotGateReads(t *testing.T) {
+	env := pinnedEnv(t)
+	files := map[string]string{"a.md": entField(`"001"`, "backlog", "verdict", "MAYBE")}
+	root := validationFixture(t, seqREADME, files)
+
+	nOut, _, nCode := runNative(t, root, env, "--workflow-dir", root)
+	if nCode != 0 {
+		t.Fatalf("default table over a warn-violation fixture must exit 0, got %d", nCode)
+	}
+	if strings.TrimSpace(nOut) == "" {
+		t.Fatalf("default table must still print the table on stdout, got empty")
+	}
+}
+
+// TestFieldConformanceSchemaDriven locks AC-4: the validator's rule and the
+// schema file agree. The test loads the embedded schema bytes independently,
+// parses out the mod-block pattern, and asserts the validator's loaded pattern
+// equals it — two independently-readable values that could diverge.
+func TestFieldConformanceSchemaDriven(t *testing.T) {
+	// Independently parse the embedded schema for the mod-block pattern.
+	var doc struct {
+		Frontmatter struct {
+			Fields map[string]struct {
+				Pattern      string   `yaml:"pattern"`
+				Conventional []string `yaml:"conventional"`
+			} `yaml:"fields"`
+		} `yaml:"frontmatter"`
+	}
+	if err := yaml.Unmarshal(spacedock.EntityMDSchema, &doc); err != nil {
+		t.Fatalf("parse embedded schema: %v", err)
+	}
+	wantPattern := doc.Frontmatter.Fields["mod-block"].Pattern
+	if wantPattern == "" {
+		t.Fatalf("embedded schema has no mod-block pattern")
+	}
+
+	schema := loadEntitySchema()
+	gotPattern := schema.fields["mod-block"].Pattern
+	if gotPattern != wantPattern {
+		t.Fatalf("validator mod-block pattern %q != schema file pattern %q", gotPattern, wantPattern)
+	}
+
+	// Same for the verdict conventional enum.
+	wantEnum := doc.Frontmatter.Fields["verdict"].Conventional
+	gotEnum := schema.fields["verdict"].Conventional
+	if strings.Join(gotEnum, ",") != strings.Join(wantEnum, ",") {
+		t.Fatalf("validator verdict enum %v != schema file enum %v", gotEnum, wantEnum)
+	}
+}
diff --git a/internal/status/handlers.go b/internal/status/handlers.go
index a122391b..3db73377 100644
--- a/internal/status/handlers.go
+++ b/internal/status/handlers.go
@@ -365,9 +365,15 @@ func runRead(probe claudeteam.TeamStateProbe, roots roots, args []string, e env,
 		if len(incompatible) > 0 {
 			return errExit(stderr, "--validate cannot be combined with "+strings.Join(incompatible, ", "))
 		}
-		// Explicit --validate command opts INTO the external-proof sub-check.
-		// The read-path pre-check (failOnValidationErrors) passes false.
-		errs := validateWorkflow(roots.definitionDir, roots.entityDir, idStyle, true, stderr)
+		// Explicit --validate command opts INTO the external-proof sub-check and
+		// the warn-tier per-field schema-conformance sub-check. The read-path
+		// pre-check (failOnValidationErrors) passes false, opting out of both.
+		errs, warns := validateWorkflow(roots.definitionDir, roots.entityDir, idStyle, true, stderr)
+		// Warn-tier per-field schema conformance prints to stderr but does NOT
+		// flip the exit code — exit 1 stays reserved for structural errors.
+		for _, w := range warns {
+			fmt.Fprintln(stderr, w)
+		}
 		if len(errs) > 0 {
 			for _, er := range errs {
 				fmt.Fprintln(stderr, er)
diff --git a/internal/status/native_runner.go b/internal/status/native_runner.go
index 84637999..6b7e74b1 100644
--- a/internal/status/native_runner.go
+++ b/internal/status/native_runner.go
@@ -355,7 +355,10 @@ func failOnValidationErrors(roots roots, idStyle string, stderr io.Writer) int {
 	// / `--next` / `--boot` / `--next-id` — those are the surfaces they need to
 	// SEE the broken entity. The terminal-set guard in runSet still classifies
 	// directly, and the explicit `--validate` command opts the check in.
-	errs := validateWorkflow(roots.definitionDir, roots.entityDir, idStyle, false, stderr)
+	// Read-path gate passes false: it opts OUT of the warn-tier field-conformance
+	// (and external-proof) sub-check, so a warn-tier field finding never locks the
+	// FO out of the listing they need to SEE the broken entity (warns is dropped).
+	errs, _ := validateWorkflow(roots.definitionDir, roots.entityDir, idStyle, false, stderr)
 	if len(errs) > 0 {
 		for _, err := range errs {
 			fmt.Fprintln(stderr, err)
diff --git a/internal/status/validate.go b/internal/status/validate.go
index b8cfd945..0f1c412d 100644
--- a/internal/status/validate.go
+++ b/internal/status/validate.go
@@ -15,12 +15,20 @@ import (
 // entityEvidence formats the Error: ... workflow= scope= slug= id= [display=]
 // path= evidence line. Matches entity_evidence.
 func entityEvidence(e *entity, workflowDir, problem, displayID string) string {
+	return entityEvidenceLine("Error", e, workflowDir, problem, displayID)
+}
+
+// entityEvidenceLine formats an evidence line at the given severity prefix
+// ("Error" for gating structural defects, "Warning" for warn-tier field
+// conformance). The field shape (workflow=/scope=/slug=/id=/[display=]/path=) is
+// identical so the FO locates the entity the same way for either severity.
+func entityEvidenceLine(severity string, e *entity, workflowDir, problem, displayID string) string {
 	display := displayID
 	if display == "" {
 		display = e.displayID
 	}
 	parts := []string{
-		fmt.Sprintf("Error: %s:", problem),
+		fmt.Sprintf("%s: %s:", severity, problem),
 		"workflow=" + workflowDir,
 		"scope=" + scopeOf(e),
 		"slug=" + e.slug,
@@ -143,8 +151,7 @@ func validateWorkflowStageNames(definitionDir string) []string {
 // status/--next/--boot/--next-id) never fires the AC classifier. A read path
 // failing on a flagged AC would lock the FO out of the very listing they need
 // to see the broken entity.
-func validateWorkflow(definitionDir, entityDir, idStyle string, includeExternalProof bool, stderr io.Writer) []string {
-	var errs []string
+func validateWorkflow(definitionDir, entityDir, idStyle string, includeExternalProof bool, stderr io.Writer) (errs []string, warns []string) {
 	errs = append(errs, findEntityFormConflicts(entityDir, entityDir, "active")...)
 	errs = append(errs, findEntityFormConflicts(filepath.Join(entityDir, "_archive"), PyJoin(entityDir, "_archive"), "archived")...)
 	errs = append(errs, validateWorkflowStageNames(definitionDir)...)
@@ -165,9 +172,17 @@ func validateWorkflow(definitionDir, entityDir, idStyle string, includeExternalP
 	}
 
 	if !includeExternalProof {
-		return errs
+		return errs, nil
 	}
 
+	// Warn-tier per-field schema conformance shares the same opt-in as the
+	// external-proof sub-check: only the explicit --validate command computes it,
+	// reusing the entities already enumerated above (with effective ids applied so
+	// the evidence line carries the display id). Warns are returned separately so
+	// the caller keeps them out of the exit-code decision.
+	applyEffectiveIDs(entities, idStyle, entities)
+	warns = fieldConformanceWarnings(entities, entityDir)
+
 	// require-external-proof sub-check: when the workflow opts in, every
 	// active entity is classified and each flagged AC is emitted as a standard
 	// entityEvidence line. A typo in the README key is surfaced as the same
@@ -175,7 +190,7 @@ func validateWorkflow(definitionDir, entityDir, idStyle string, includeExternalP
 	policy, perr := resolveExternalProofPolicy(definitionDir)
 	if perr != nil {
 		errs = append(errs, "Error: "+perr.Error())
-		return errs
+		return errs, warns
 	}
 	if policy == externalProofOn {
 		for _, e := range entities {
@@ -193,7 +208,7 @@ func validateWorkflow(definitionDir, entityDir, idStyle string, includeExternalP
 		}
 	}
 
-	return errs
+	return errs, warns
 }
 
 func validateSequential(entities []*entity, workflowDir string) []string {
diff --git a/schema_embed.go b/schema_embed.go
new file mode 100644
index 00000000..b4e7127a
--- /dev/null
+++ b/schema_embed.go
@@ -0,0 +1,14 @@
+// ABOUTME: Embeds the canonical entity mdschema (the frontmatter SSOT) into the
+// ABOUTME: binary so field-conformance validation has no runtime docs/ dependency.
+package spacedock
+
+import _ "embed"
+
+// EntityMDSchema is the bytes of docs/schema/entity.mdschema.yml, the single
+// source of truth for the entity frontmatter contract. It is embedded here at
+// the module root because go:embed cannot reach a file above the embedding
+// package's directory; embedding the canonical file (rather than a copy) keeps
+// one source of truth that the validator reads at run time.
+//
+//go:embed docs/schema/entity.mdschema.yml
+var EntityMDSchema []byte