feat(agent): include platform self identities in system prompts

Give bots their known per-channel account handles in the system prompt so they can reason about platform-specific self references consistently. Reuse persisted channel self_identity data across chat, discuss, schedule, heartbeat, and subagent prompts.

internal/agent/prompt.go

@@ -47,6 +47,7 @@ func init() {
 		"_memory":        mustReadPrompt("prompts/_memory.md"),
 		"_tools":         mustReadPrompt("prompts/_tools.md"),
 		"_contacts":      mustReadPrompt("prompts/_contacts.md"),
+		"_identities":    mustReadPrompt("prompts/_identities.md"),
 		"_schedule_task": mustReadPrompt("prompts/_schedule_task.md"),
 		"_subagent":      mustReadPrompt("prompts/_subagent.md"),
 	}
@@ -144,23 +145,25 @@ func GenerateSystemPrompt(params SystemPromptParams) string {
 	tmpl := selectSystemTemplate(params.SessionType)
 
 	return render(tmpl, map[string]string{
-		"home":          home,
-		"currentTime":   now.Format(time.RFC3339),
-		"timezone":      timezoneName,
-		"basicTools":    strings.Join(basicTools, "\n"),
-		"skillsSection": skillsSection,
-		"fileSections":  fileSections,
+		"home":                      home,
+		"currentTime":               now.Format(time.RFC3339),
+		"timezone":                  timezoneName,
+		"basicTools":                strings.Join(basicTools, "\n"),
+		"skillsSection":             skillsSection,
+		"platformIdentitiesSection": strings.TrimSpace(params.PlatformIdentitiesSection),
+		"fileSections":              fileSections,
 	})
 }
 
 // SystemPromptParams holds all inputs for system prompt generation.
 type SystemPromptParams struct {
-	SessionType        string
-	Skills             []SkillEntry
-	Files              []SystemFile
-	Now                time.Time
-	Timezone           string
-	SupportsImageInput bool
+	SessionType               string
+	Skills                    []SkillEntry
+	Files                     []SystemFile
+	Now                       time.Time
+	Timezone                  string
+	SupportsImageInput        bool
+	PlatformIdentitiesSection string
 }
 
 // GenerateSchedulePrompt builds the user message for a scheduled task trigger.

internal/agent/prompt_test.go

@@ -0,0 +1,43 @@
+package agent
+
+import (
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestGenerateSystemPromptIncludesPlatformIdentitiesInChat(t *testing.T) {
+	t.Parallel()
+
+	prompt := GenerateSystemPrompt(SystemPromptParams{
+		SessionType:               "chat",
+		Now:                       time.Unix(1, 0).UTC(),
+		Timezone:                  "UTC",
+		PlatformIdentitiesSection: "## Platform Identities\n\n<identity channel=\"telegram\" username=\"@memoh\"/>",
+	})
+
+	if !strings.Contains(prompt, "## Platform Identities") {
+		t.Fatalf("expected platform identities heading in prompt")
+	}
+	if !strings.Contains(prompt, `<identity channel="telegram" username="@memoh"/>`) {
+		t.Fatalf("expected platform identity XML in prompt")
+	}
+}
+
+func TestGenerateSystemPromptIncludesPlatformIdentitiesInDiscuss(t *testing.T) {
+	t.Parallel()
+
+	prompt := GenerateSystemPrompt(SystemPromptParams{
+		SessionType:               "discuss",
+		Now:                       time.Unix(1, 0).UTC(),
+		Timezone:                  "UTC",
+		PlatformIdentitiesSection: "## Platform Identities\n\n<identity channel=\"discord\" username=\"@memoh\"/>",
+	})
+
+	if !strings.Contains(prompt, "## Platform Identities") {
+		t.Fatalf("expected platform identities heading in discuss prompt")
+	}
+	if !strings.Contains(prompt, `<identity channel="discord" username="@memoh"/>`) {
+		t.Fatalf("expected platform identity XML in discuss prompt")
+	}
+}

internal/agent/prompts/_identities.md

@@ -0,0 +1 @@
+{{platformIdentitiesSection}}

internal/agent/prompts/system_chat.md

@@ -43,6 +43,8 @@ You are in **chat mode** — your text output IS your reply. Whatever you write
 
 {{include:_contacts}}
 
+{{include:_identities}}
+
 ## Message Format
 
 User messages are wrapped in `<message>` XML tags with metadata attributes:

internal/agent/prompts/system_discuss.md

@@ -60,6 +60,8 @@ Not every message needs a response. Staying silent is valid and often appropriat
 
 {{include:_contacts}}
 
+{{include:_identities}}
+
 ## Message Format
 
 Chat history appears as XML in your conversation. Each message looks like:

internal/agent/prompts/system_heartbeat.md

@@ -20,6 +20,8 @@ You are in **heartbeat mode** — a periodic system-triggered check. There is no
 
 {{include:_contacts}}
 
+{{include:_identities}}
+
 ## The HEARTBEAT_OK Contract
 
 - If nothing needs attention, reply with exactly `HEARTBEAT_OK`.

internal/agent/prompts/system_schedule.md

@@ -20,6 +20,8 @@ You are in **schedule mode** — executing a scheduled task. There is no active
 
 {{include:_contacts}}
 
+{{include:_identities}}
+
 ## How to Deliver Results
 
 Use `send` to deliver results to the intended channel — there is no active conversation to reply to. Use `get_contacts` to find the right target.

internal/agent/prompts/system_subagent.md

@@ -18,3 +18,5 @@ You have access to:
 - Do NOT create schedules or manage memory
 - Keep private data private
 - Don't run destructive commands without necessity
+
+{{include:_identities}}