v0.116.0: observability pass — always-on debug ring + leveled sweep + agent tab + self-log pull — MinAgent: 0.81.0

Capture layer: LogBuffer always exists; logger = MultiWriter(LevelFilterWriter
(stdout, logging.level), ring) so DEBUG detail exists remotely without a config
flip while docker logs keep respecting the level. New internal/logx leveled
helpers. Report ACK gains controller_log_requested (additive); next report
ships controller_log_tail (128KB, consume-once, app-tail wire byte-compatible).
Debug page: Vezérlő|Ügynök tabs; agent tab proxies agent /debug/logs with the
pre-0.83 notice on typed 404. Sweep: netstorage_job phases, netprobe, handler
validation refusals + orphan WARN, SupportsWithSource gate line, agentapi
per-call DEBUG, migrate phase lines, tier2/offbox unswallowed persists.
Red-proofs: filter-disabled, drain-removed, dropped-phase-line all FAIL.

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

controller/internal/agentapi/client.go

@@ -16,11 +16,14 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"log"
 	"net/http"
 	"regexp"
 	"strings"
 	"sync"
 	"time"
+
+	"gitea.dooplex.hu/admin/felhom-controller/internal/logx"
 )
 
 // Client talks to one agent local-API endpoint with a pinned leaf + bearer token.
@@ -35,8 +38,15 @@ type Client struct {
 	// Supports falls back to the route probe.
 	verMu            sync.Mutex
 	lastAgentVersion string
+	// logger is the optional per-call DEBUG trace sink (v0.116.0 observability — the
+	// capture ring holds these even at logging.level=info). nil = silent (unchanged).
+	logger *log.Logger
 }
 
+// SetLogger wires the optional per-call DEBUG trace logger (method, path, status,
+// duration + agent-version changes — never bodies or tokens).
+func (c *Client) SetLogger(l *log.Logger) { c.logger = l }
+
 // 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.
@@ -50,8 +60,12 @@ func (c *Client) noteAgentVersion(resp *http.Response) {
 		return
 	}
 	c.verMu.Lock()
+	prev := c.lastAgentVersion
 	c.lastAgentVersion = v
 	c.verMu.Unlock()
+	if prev != v {
+		logx.Debugf(c.logger, "[agentapi] agent version seen: %s (was %q)", v, prev)
+	}
 }
 
 // AgentVersion returns the last strictly-validated agent version seen on this client's traffic
@@ -799,12 +813,15 @@ func (c *Client) postWithStatus(ctx context.Context, path string, body any) (api
 	}
 	req.Header.Set("Authorization", "Bearer "+c.token)
 	req.Header.Set("Content-Type", "application/json")
+	start := time.Now()
 	resp, err := c.hc.Do(req)
 	if err != nil {
+		logx.Debugf(c.logger, "[agentapi] POST %s failed after %dms: %v", path, time.Since(start).Milliseconds(), err)
 		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
+	logx.Debugf(c.logger, "[agentapi] POST %s -> %d (%dms)", path, resp.StatusCode, time.Since(start).Milliseconds())
 	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)
@@ -812,6 +829,37 @@ func (c *Client) postWithStatus(ctx context.Context, path string, body any) (api
 	return env, resp.StatusCode, nil
 }
 
+// ---- v0.116.0: agent debug-log ring (the Debug page agent tab) ----------------------------
+
+// AgentLogEntry mirrors the agent's GET /debug/logs entry (agent ≥ 0.83.0).
+type AgentLogEntry struct {
+	Timestamp time.Time `json:"timestamp"`
+	Level     string    `json:"level"`
+	Message   string    `json:"message"`
+}
+
+// AgentLogsResponse mirrors the agent's GET /debug/logs data payload.
+type AgentLogsResponse struct {
+	VMID    int             `json:"vmid"`
+	Entries []AgentLogEntry `json:"entries"`
+	Total   int             `json:"total"`
+}
+
+// DebugLogs fetches the agent's always-DEBUG capture ring. Against a pre-0.83
+// agent the route is absent → a typed *StatusError with Code 404 (the caller
+// renders the "available after the agent's next update" notice — S6).
+func (c *Client) DebugLogs(ctx context.Context) (AgentLogsResponse, error) {
+	var out AgentLogsResponse
+	data, err := c.get(ctx, "/debug/logs")
+	if err != nil {
+		return out, err
+	}
+	if err := json.Unmarshal(data, &out); err != nil {
+		return out, fmt.Errorf("agentapi: parsing debug logs: %w", err)
+	}
+	return out, nil
+}
+
 // ---- slice 9: host metrics (the customer host-health view) -------------------------------
 
 // HostMetrics mirrors the agent's GET /host/metrics `host` block (shared HostMetrics wire shape).
@@ -908,12 +956,15 @@ func (c *Client) get(ctx context.Context, path string) (json.RawMessage, error)
 		return nil, err
 	}
 	req.Header.Set("Authorization", "Bearer "+c.token)
+	start := time.Now()
 	resp, err := c.hc.Do(req)
 	if err != nil {
+		logx.Debugf(c.logger, "[agentapi] GET %s failed after %dms: %v", path, time.Since(start).Milliseconds(), err)
 		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
+	logx.Debugf(c.logger, "[agentapi] GET %s -> %d (%dms)", path, resp.StatusCode, time.Since(start).Milliseconds())
 	raw, _ := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
 	if resp.StatusCode != http.StatusOK {
 		return nil, &StatusError{Path: path, Code: resp.StatusCode}
@@ -941,12 +992,15 @@ func (c *Client) post(ctx context.Context, path string, body any) (json.RawMessa
 	}
 	req.Header.Set("Authorization", "Bearer "+c.token)
 	req.Header.Set("Content-Type", "application/json")
+	start := time.Now()
 	resp, err := c.hc.Do(req)
 	if err != nil {
+		logx.Debugf(c.logger, "[agentapi] POST %s failed after %dms: %v", path, time.Since(start).Milliseconds(), err)
 		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
+	logx.Debugf(c.logger, "[agentapi] POST %s -> %d (%dms)", path, resp.StatusCode, time.Since(start).Milliseconds())
 	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)