v0.115.0: version-aware Supports (agent header channel) + DSM-validated NFS guidance — MinAgent: 0.81.0

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PSK5g6qYLknKj8u3QAFEr6

controller/internal/agentapi/client.go

@@ -17,7 +17,9 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"regexp"
 	"strings"
+	"sync"
 	"time"
 )
 
@@ -28,6 +30,36 @@ type Client struct {
 	hc      *http.Client
 	// features caches capability-probe verdicts for Supports (features.go).
 	features SupportCache
+	// verMu guards lastAgentVersion — the most recent STRICTLY-VALIDATED X-Felhom-Agent-Version
+	// seen on any agent response (v0.82.0 version channel). "" = never seen (pre-0.82 agent) →
+	// Supports falls back to the route probe.
+	verMu            sync.Mutex
+	lastAgentVersion string
+}
+
+// reAgentVersion is the bare-semver shape the publish pipeline enforces (publish-agent.sh) — the
+// ONLY header values trusted for capability comparison. Anything else (garbage, "dev", suffixes)
+// is ignored and the probe fallback stays in charge.
+var reAgentVersion = regexp.MustCompile(`^[0-9]+\.[0-9]+\.[0-9]+$`)
+
+// noteAgentVersion records a response's version header (passive capture — called on EVERY response
+// path). Invalid/absent headers never overwrite a previously-seen valid version.
+func (c *Client) noteAgentVersion(resp *http.Response) {
+	v := strings.TrimSpace(resp.Header.Get("X-Felhom-Agent-Version"))
+	if v == "" || !reAgentVersion.MatchString(v) {
+		return
+	}
+	c.verMu.Lock()
+	c.lastAgentVersion = v
+	c.verMu.Unlock()
+}
+
+// AgentVersion returns the last strictly-validated agent version seen on this client's traffic
+// ("" = unknown — header-less agent or no traffic yet). This is the Supports comparison source.
+func (c *Client) AgentVersion() string {
+	c.verMu.Lock()
+	defer c.verMu.Unlock()
+	return c.lastAgentVersion
 }
 
 // MountInfo mirrors the agent's GET /storage mount entry (doc 03 §6).
@@ -491,6 +523,7 @@ func (c *Client) WipeStagedEscrowSecret(ctx context.Context) error {
 		return fmt.Errorf("agentapi: DELETE /escrow/stage-secret: %w", err)
 	}
 	defer resp.Body.Close()
+	c.noteAgentVersion(resp) // v0.82.0 version channel: passive capture on EVERY response
 	raw, _ := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
 	var env apiResponse
 	if err := json.Unmarshal(raw, &env); err != nil {
@@ -771,6 +804,7 @@ func (c *Client) postWithStatus(ctx context.Context, path string, body any) (api
 		return env, 0, fmt.Errorf("agentapi: POST %s: %w", path, err)
 	}
 	defer resp.Body.Close()
+	c.noteAgentVersion(resp) // v0.82.0 version channel: passive capture on EVERY response
 	raw, _ := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
 	if err := json.Unmarshal(raw, &env); err != nil {
 		return env, resp.StatusCode, fmt.Errorf("agentapi: POST %s: HTTP %d, bad envelope: %w", path, resp.StatusCode, err)
@@ -879,6 +913,7 @@ func (c *Client) get(ctx context.Context, path string) (json.RawMessage, error)
 		return nil, fmt.Errorf("agentapi: GET %s: %w", path, err)
 	}
 	defer resp.Body.Close()
+	c.noteAgentVersion(resp) // v0.82.0 version channel: passive capture on EVERY response
 	raw, _ := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
 	if resp.StatusCode != http.StatusOK {
 		return nil, &StatusError{Path: path, Code: resp.StatusCode}
@@ -911,6 +946,7 @@ func (c *Client) post(ctx context.Context, path string, body any) (json.RawMessa
 		return nil, fmt.Errorf("agentapi: POST %s: %w", path, err)
 	}
 	defer resp.Body.Close()
+	c.noteAgentVersion(resp) // v0.82.0 version channel: passive capture on EVERY response
 	raw, _ := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
 	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusAccepted {
 		return nil, fmt.Errorf("agentapi: POST %s: HTTP %d", path, resp.StatusCode)