fix(agent-update): stop stripping the pre-release suffix from the bundled agent version

util.GetVersionFromBinaryPath parsed the bundled agent binary with a regex that
captured only MAJOR.MINOR.PATCH, so an edge binary stamped 2.0.3-rc.116 was read
as "2.0.3". That value is what ServeAgentVersion advertises as latestVersion, and
CompareVersions correctly ranks a release above its pre-release, so once a host
had actually installed the rc the server kept reporting hasUpdate: true and the
agent re-downloaded the identical binary on every check.

handler/agent_version.go already carried the corrected pattern along with a
comment describing this exact failure; the util copy was never updated and the
two drifted. Promote the pattern to util.AgentVersionRe and alias the handler
constant to it so there is only one definition, which also means the existing
TestAgentVersionRe_CapturesPreRelease now guards both call sites.

alerts/agent_update.go shares the same helper, so the "Agent Files Update
Available" alert was likewise comparing a truncated current version against the
full DNS value.

Upgrades from an older release are unaffected: the numeric core decides before
the pre-release identifiers are consulted, so 2.0.2 still sees 2.0.3-rc.116 as an
update.

Author: 9technologygroup

server-source-code/internal/handler/agent_version.go

@@ -18,12 +18,10 @@ import (
 
 const (
 	agentDNSDomain = "agent.vcheck.patchmon.net"
-	// The pre-release group is required, not cosmetic: edge agents are stamped
-	// 2.0.3-rc.61, and capturing only the numeric core would report them as
-	// "2.0.3" here while the agent itself reports the full string. The two would
-	// never match, so every check would look like a pending update and the agent
-	// would re-download itself forever.
-	agentVersionRe = `(?i)(?:PatchMon Agent v|patchmon-agent v|version )?([0-9]+\.[0-9]+\.[0-9]+(?:-[0-9A-Za-z.-]+)?)`
+	// Shared with util.GetVersionFromBinaryPath, which backs the agent's own
+	// update check. Two copies drifted apart once and stripped the pre-release
+	// suffix on the update path only; keep this an alias, not a duplicate.
+	agentVersionRe = util.AgentVersionRe
 )
 
 // AgentVersionHandler handles agent version routes.

server-source-code/internal/util/agent_binary.go

@@ -11,7 +11,13 @@ import (
 	"time"
 )
 
-const agentVersionRe = `(?i)(?:PatchMon Agent v|patchmon-agent v|version )?([0-9]+\.[0-9]+\.[0-9]+)`
+// AgentVersionRe parses a version out of an agent binary's own output. The
+// pre-release group is required, not cosmetic: edge agents are stamped
+// 2.0.3-rc.61, and capturing only the numeric core reports them as "2.0.3"
+// here while the agent itself reports the full string. The server then
+// advertises a latestVersion that always outranks what the agent has, so every
+// check looks like a pending update and the agent re-downloads itself forever.
+const AgentVersionRe = `(?i)(?:PatchMon Agent v|patchmon-agent v|version )?([0-9]+\.[0-9]+\.[0-9]+(?:-[0-9A-Za-z.-]+)?)`
 
 // GetAgentsDir returns the agents binary directory from env (AGENT_BINARIES_DIR, AGENTS_DIR) or "agents".
 func GetAgentsDir() string {
@@ -59,7 +65,7 @@ func GetCurrentAgentVersionFromBinary(ctx context.Context, agentsDir string) str
 		return ""
 	}
 
-	versionRe := regexp.MustCompile(agentVersionRe)
+	versionRe := regexp.MustCompile(AgentVersionRe)
 	versionCommands := []string{"--version", "version", "--help"}
 
 	for _, cmd := range versionCommands {
@@ -80,7 +86,7 @@ func GetCurrentAgentVersionFromBinary(ctx context.Context, agentsDir string) str
 // Tries executing the binary if it matches server platform (linux/linux, freebsd/freebsd), else uses "strings".
 // Callers must pass binaryPath validated with SafePathUnderBase(baseDir, binaryName) to prevent command injection.
 func GetVersionFromBinaryPath(ctx context.Context, binaryPath string) string {
-	versionRe := regexp.MustCompile(agentVersionRe)
+	versionRe := regexp.MustCompile(AgentVersionRe)
 	serverOS := runtime.GOOS
 	binaryOS := "linux"
 	if strings.Contains(binaryPath, "freebsd") {