starpod-agent 0.3.1

//! Background nudge — periodically reviews the conversation and persists
//! important information to durable memory and, optionally, skills.
//!
//! Every [`nudge_interval`](starpod_core::MemoryConfig::nudge_interval) user
//! messages, a lightweight LLM call reviews the recent conversation transcript
//! (pulled from session messages) and uses `MemoryWrite` / `MemoryAppendDaily`
//! tools to save anything worth keeping.
//!
//! When **self-improve** is enabled, the same background call also receives
//! `SkillCreate` / `SkillUpdate` tools and guidance for extracting reusable
//! skills from complex tasks — unifying memory and skill learning in a single
//! pass.
//!
//! Unlike the pre-compaction flush ([`flush`](crate::flush)) which fires when
//! the context window fills, the nudge runs **proactively** on a cadence so
//! information is captured even in short conversations that never hit
//! compaction.
//!
//! # How it works
//!
//! 1. `StarpodAgent` keeps a per-session message counter
//!    (`nudge_counters`). After each user message, the counter increments.
//! 2. When `count % nudge_interval == 0`, [`StarpodAgent::maybe_nudge_memory`]
//!    loads the full session transcript from the database.
//! 3. When a session closes with un-nudged messages (counter > 0 but hasn't
//!    hit the interval), a **final nudge** runs so short conversations are
//!    never lost.
//! 4. When a user sends a message to any session,
//!    [`StarpodAgent::flush_stale_sessions`] checks for other sessions
//!    belonging to the same user with un-nudged messages and flushes them.
//!    This catches the web UI pattern where sessions are never closed.
//! 5. A background `tokio::spawn` task calls [`run_nudge`] which:
//!    - Converts `SessionMessage` records into a human-readable transcript
//!    - Makes a single non-streaming LLM call with memory tools (and skill
//!      tools when self-improve is on)
//!    - Executes any `MemoryWrite` / `MemoryAppendDaily` tool calls from the
//!      response (via [`flush::execute_flush_tool_calls`])
//!    - Executes any `SkillCreate` / `SkillUpdate` tool calls against the
//!      [`SkillStore`](starpod_skills::SkillStore)
//!    - Discards the LLM's text output — only tool calls matter
//!
//! # Configuration
//!
//! - `memory.nudge_interval` (default `10`) — user messages between nudges;
//!   set to `0` to disable
//! - `memory.nudge_model` — model override; falls back to
//!   `compaction.flush_model` → `compaction_model` → primary model
//! - `self_improve` (top-level) — when `true`, skill tools are included in the
//!   nudge call
//!
//! # Failure mode
//!
//! Fail-open: if the provider call fails or the LLM returns no tool calls, a
//! warning is logged and the conversation continues unaffected.

use std::sync::Arc;

use tracing::{debug, warn};

use agent_sdk::client::{
    ApiContentBlock, ApiMessage, CreateMessageRequest, SystemBlock, ToolDefinition,
};
use agent_sdk::LlmProvider;
use starpod_memory::MemoryStore;
use starpod_memory::UserMemoryView;
use starpod_session::SessionMessage;
use starpod_skills::SkillStore;

use crate::flush;

/// Base system prompt for the background nudge (memory-only portion).
///
/// Instructs the LLM to act as a memory management agent, reviewing the
/// conversation transcript and deciding what to persist. Guides routing:
/// user details → `USER.md`, factual knowledge → `MEMORY.md`, temporal
/// notes → daily log.
const NUDGE_SYSTEM_PROMPT: &str = "\
You are a background review agent. Your ONLY job is to review the recent conversation \
and save important information using the provided tools. Be selective — only save \
information that would be useful in future conversations.

Save these kinds of information:
- User preferences, working style, and personal details → USER.md
- Key decisions and their reasoning → MEMORY.md (append)
- Important facts, names, dates, and relationships → MEMORY.md (append)
- Technical context: architecture choices, conventions, configurations → MEMORY.md (append)
- Action items, commitments, and follow-ups → daily log
- Brief summary of what was discussed → daily log

Do NOT save:
- Trivial or transient exchanges (greetings, acknowledgments, small talk)
- Information that's already in MEMORY.md or USER.md
- Raw code or long outputs (summarize instead)
- Temporary debugging context or error traces

If there is nothing worth saving, respond with a single text message saying \
\"Nothing to save\" and make no tool calls.

Use MemoryWrite with append=true to add to MEMORY.md or USER.md. \
Use MemoryAppendDaily for time-specific notes and conversation summaries. \
Respond with ONLY tool calls (or \"Nothing to save\"), no other text.";

/// Additional system prompt appended when self-improve is enabled.
///
/// Guides the nudge LLM to also create or update skills when the conversation
/// contains complex workflows, non-trivial patterns, or reveals that an
/// existing skill is outdated.
const NUDGE_SKILL_PROMPT: &str = "\n\n\
--- SKILL SELF-IMPROVE ---\n\
You also have skill management tools. Review the conversation for skill opportunities:\n\n\
SKILL CREATION:\n\
If the conversation involved a complex task (roughly 5+ tool calls), a tricky error fix, \
or a non-trivial workflow, save the approach as a reusable skill with SkillCreate. \
Include clear steps, context on when to use it, and pitfalls encountered. \
Do NOT create skills for trivial or one-off tasks.\n\n\
SKILL UPDATES:\n\
If the conversation used an existing skill and found it outdated, incomplete, or wrong, \
update it with SkillUpdate. Skills that aren't maintained become liabilities.\n\n\
Skill names must be lowercase letters, digits, and hyphens only (e.g. 'summarize-pr').";

/// Tool definitions for `SkillCreate` and `SkillUpdate`, used by the nudge
/// when self-improve is enabled.
fn skill_tool_definitions() -> Vec<ToolDefinition> {
    vec![
        ToolDefinition {
            name: "SkillCreate".into(),
            description: "Create a new reusable skill. Skills are SKILL.md files with YAML \
                          frontmatter (name, description) and a markdown body."
                .into(),
            input_schema: serde_json::json!({
                "type": "object",
                "properties": {
                    "name": {
                        "type": "string",
                        "description": "Skill name (lowercase letters, digits, hyphens only, e.g. 'summarize-pr')"
                    },
                    "description": {
                        "type": "string",
                        "description": "What the skill does and when to use it"
                    },
                    "body": {
                        "type": "string",
                        "description": "Markdown instructions for the skill"
                    }
                },
                "required": ["name", "description", "body"]
            }),
            cache_control: None,
        },
        ToolDefinition {
            name: "SkillUpdate".into(),
            description: "Update an existing skill's description and instructions.".into(),
            input_schema: serde_json::json!({
                "type": "object",
                "properties": {
                    "name": {
                        "type": "string",
                        "description": "Name of the skill to update"
                    },
                    "description": {
                        "type": "string",
                        "description": "New description for the skill"
                    },
                    "body": {
                        "type": "string",
                        "description": "New markdown instructions for the skill"
                    }
                },
                "required": ["name", "description", "body"]
            }),
            cache_control: None,
        },
    ]
}

/// Build the full system prompt for the nudge, optionally including skill
/// guidance and the current skill catalog.
fn build_nudge_system_prompt(skills: Option<&SkillStore>) -> String {
    let mut prompt = NUDGE_SYSTEM_PROMPT.to_string();

    if let Some(store) = skills {
        prompt.push_str(NUDGE_SKILL_PROMPT);

        // Include existing skill catalog so the LLM knows what already exists
        if let Ok(catalog) = store.skill_catalog() {
            if !catalog.is_empty() {
                prompt.push_str(
                    "\n\nExisting skills (update these rather than creating duplicates):\n",
                );
                prompt.push_str(&catalog);
            }
        }
    }

    prompt
}

/// Execute `SkillCreate` / `SkillUpdate` tool calls from the LLM response.
///
/// Skips unknown tool names silently (memory tools are handled separately by
/// [`flush::execute_flush_tool_calls`]).
fn execute_skill_tool_calls(content: &[ApiContentBlock], skills: &SkillStore) {
    for block in content {
        if let ApiContentBlock::ToolUse { name, input, id } = block {
            match name.as_str() {
                "SkillCreate" => {
                    let Some(skill_name) = input.get("name").and_then(|v| v.as_str()) else {
                        continue;
                    };
                    let Some(description) = input.get("description").and_then(|v| v.as_str())
                    else {
                        continue;
                    };
                    let Some(body) = input.get("body").and_then(|v| v.as_str()) else {
                        continue;
                    };

                    debug!(tool_id = %id, skill = %skill_name, "Nudge: creating skill");
                    if let Err(e) = skills.create(skill_name, description, None, None, body) {
                        warn!(skill = %skill_name, error = %e, "Nudge: SkillCreate failed");
                    }
                }
                "SkillUpdate" => {
                    let Some(skill_name) = input.get("name").and_then(|v| v.as_str()) else {
                        continue;
                    };
                    let Some(description) = input.get("description").and_then(|v| v.as_str())
                    else {
                        continue;
                    };
                    let Some(body) = input.get("body").and_then(|v| v.as_str()) else {
                        continue;
                    };

                    debug!(tool_id = %id, skill = %skill_name, "Nudge: updating skill");
                    if let Err(e) = skills.update(skill_name, description, None, None, body) {
                        warn!(skill = %skill_name, error = %e, "Nudge: SkillUpdate failed");
                    }
                }
                _ => {} // Memory tools handled by flush::execute_flush_tool_calls
            }
        }
    }
}

/// Maximum transcript length sent to the nudge LLM (characters).
const MAX_TRANSCRIPT_LEN: usize = 30_000;

/// Maximum length of a single message in the transcript (characters).
const MAX_MESSAGE_LEN: usize = 1_000;

/// Convert session messages into a human-readable transcript for the nudge LLM.
///
/// Each message is formatted as `[role] content` with double-newline separators.
/// Individual messages exceeding [`MAX_MESSAGE_LEN`] are truncated with `...`.
fn session_messages_to_transcript(messages: &[SessionMessage]) -> String {
    let mut parts = Vec::with_capacity(messages.len());
    for msg in messages {
        let role = match msg.role.as_str() {
            "user" => "user",
            "assistant" => "assistant",
            "tool_use" => "assistant (tool_use)",
            "tool_result" => "tool_result",
            other => other,
        };
        // Truncate very long messages (e.g. tool results with big outputs)
        let content = if msg.content.len() > MAX_MESSAGE_LEN {
            let mut end = MAX_MESSAGE_LEN;
            while end > 0 && !msg.content.is_char_boundary(end) {
                end -= 1;
            }
            format!("{}...", &msg.content[..end])
        } else {
            msg.content.clone()
        };
        parts.push(format!("[{}] {}", role, content));
    }
    parts.join("\n\n")
}

/// Run the background nudge.
///
/// Builds a transcript from `messages`, sends it to the LLM via a single
/// non-streaming call, then executes any tool calls from the response.
///
/// When `skills` is `Some`, the nudge also includes `SkillCreate` /
/// `SkillUpdate` tools and guidance for extracting reusable skills from
/// complex tasks (self-improve mode).
///
/// # Arguments
///
/// * `provider` — LLM provider (shared ownership for use across `tokio::spawn`)
/// * `model` — model ID to use for the nudge call
/// * `messages` — session messages to review (from `SessionManager::get_messages`)
/// * `memory` — agent-level memory store (writes land here when no user view)
/// * `user_view` — per-user memory view; when present, writes route to the
///   user's directory instead of the agent-level store
/// * `skills` — when `Some`, skill tools are included (self-improve mode)
///
/// # Errors
///
/// This function is fail-open: provider errors are logged as warnings, and
/// the caller is not notified. This ensures the nudge never disrupts the
/// main chat flow.
pub async fn run_nudge(
    provider: Arc<dyn LlmProvider>,
    model: &str,
    messages: &[SessionMessage],
    memory: &MemoryStore,
    user_view: Option<&UserMemoryView>,
    skills: Option<&SkillStore>,
) {
    let transcript = session_messages_to_transcript(messages);
    if transcript.trim().is_empty() {
        return;
    }

    // Cap transcript to avoid huge requests
    let transcript = if transcript.len() > MAX_TRANSCRIPT_LEN {
        let mut end = MAX_TRANSCRIPT_LEN;
        while end > 0 && !transcript.is_char_boundary(end) {
            end -= 1;
        }
        format!("{}...\n\n[transcript truncated]", &transcript[..end])
    } else {
        transcript
    };

    // Build tools: always memory, optionally skills
    let mut tools = flush::flush_tool_definitions();
    if skills.is_some() {
        tools.extend(skill_tool_definitions());
    }

    let system_prompt = build_nudge_system_prompt(skills);

    let request = CreateMessageRequest {
        model: model.to_string(),
        max_tokens: 4096,
        messages: vec![ApiMessage {
            role: "user".into(),
            content: vec![ApiContentBlock::Text {
                text: format!(
                    "Review this recent conversation and save important information:\n\n{}",
                    transcript
                ),
                cache_control: None,
            }],
        }],
        system: Some(vec![SystemBlock {
            kind: "text".into(),
            text: system_prompt,
            cache_control: None,
        }]),
        tools: Some(tools),
        stream: false,
        metadata: None,
        thinking: None,
    };

    let self_improve = skills.is_some();
    debug!(model = %model, self_improve, transcript_len = transcript.len(), messages = messages.len(), "Running background nudge");

    match provider.create_message(&request).await {
        Ok(response) => {
            let tool_calls: Vec<_> = response
                .content
                .iter()
                .filter(|b| matches!(b, ApiContentBlock::ToolUse { .. }))
                .collect();
            if tool_calls.is_empty() {
                debug!("Nudge: nothing to save");
            } else {
                debug!(tool_calls = tool_calls.len(), "Nudge: executing tool calls");
            }
            // Execute memory tool calls
            flush::execute_flush_tool_calls(&response.content, memory, user_view).await;
            // Execute skill tool calls (no-op when skills is None)
            if let Some(store) = skills {
                execute_skill_tool_calls(&response.content, store);
            }
        }
        Err(e) => {
            warn!(error = %e, "Background nudge LLM call failed");
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    use std::pin::Pin;

    use agent_sdk::client::{ApiUsage, MessageResponse, StreamEvent};
    use agent_sdk::error::Result as SdkResult;
    use agent_sdk::provider::{CostRates, ProviderCapabilities};
    use async_trait::async_trait;
    use futures::stream::Stream;

    /// Helper to build a SessionMessage with minimal boilerplate.
    fn msg(id: i64, role: &str, content: &str) -> SessionMessage {
        SessionMessage {
            id,
            session_id: "test-session".into(),
            role: role.into(),
            content: content.into(),
            timestamp: "2026-03-28T10:00:00".into(),
        }
    }

    // ── transcript formatting ─────────────────────────────────────────

    #[test]
    fn transcript_formats_session_messages() {
        let messages = vec![
            msg(1, "user", "What is Rust?"),
            msg(2, "assistant", "Rust is a systems programming language."),
        ];

        let transcript = session_messages_to_transcript(&messages);
        assert!(transcript.contains("[user] What is Rust?"));
        assert!(transcript.contains("[assistant] Rust is a systems programming language."));
    }

    #[test]
    fn transcript_separates_messages_with_double_newlines() {
        let messages = vec![msg(1, "user", "Hello"), msg(2, "assistant", "Hi there")];

        let transcript = session_messages_to_transcript(&messages);
        assert!(transcript.contains("[user] Hello\n\n[assistant] Hi there"));
    }

    #[test]
    fn transcript_truncates_long_messages() {
        let long_content = "x".repeat(2000);
        let messages = vec![msg(1, "tool_result", &long_content)];

        let transcript = session_messages_to_transcript(&messages);
        assert!(transcript.ends_with("..."));
        // Should be: "[tool_result] " (15 chars) + 1000 chars + "..." (3 chars) = ~1018
        assert!(transcript.len() < 1100);
    }

    #[test]
    fn transcript_handles_empty_messages() {
        let messages: Vec<SessionMessage> = vec![];
        let transcript = session_messages_to_transcript(&messages);
        assert!(transcript.is_empty());
    }

    #[test]
    fn transcript_maps_tool_roles() {
        let messages = vec![
            msg(1, "tool_use", "MemorySearch({\"query\": \"test\"})"),
            msg(2, "tool_result", "Found 3 results."),
        ];

        let transcript = session_messages_to_transcript(&messages);
        assert!(transcript.contains("[assistant (tool_use)]"));
        assert!(transcript.contains("[tool_result]"));
    }

    #[test]
    fn transcript_preserves_unknown_roles() {
        let messages = vec![msg(1, "system", "You are an AI assistant.")];
        let transcript = session_messages_to_transcript(&messages);
        assert!(transcript.contains("[system] You are an AI assistant."));
    }

    #[test]
    fn transcript_handles_multibyte_chars_in_truncation() {
        // 4-byte emoji repeated — truncation must not split a character
        let emoji_content = "🦀".repeat(500); // 500 * 4 = 2000 bytes
        let messages = vec![msg(1, "user", &emoji_content)];

        let transcript = session_messages_to_transcript(&messages);
        // Should not panic and should end with "..."
        assert!(transcript.ends_with("..."));
        // Verify the truncated content is valid UTF-8 (implicitly true if we got here)
        assert!(!transcript.is_empty());
    }

    #[test]
    fn transcript_single_message_no_trailing_separator() {
        let messages = vec![msg(1, "user", "Just one message")];
        let transcript = session_messages_to_transcript(&messages);
        assert_eq!(transcript, "[user] Just one message");
    }

    // ── transcript capping ───────────────────────────────────────────

    #[test]
    fn transcript_cap_applies_to_total_length() {
        // Build a transcript that exceeds MAX_TRANSCRIPT_LEN
        let long_msg = "a".repeat(800);
        let messages: Vec<_> = (0..50).map(|i| msg(i, "user", &long_msg)).collect();

        let transcript = session_messages_to_transcript(&messages);
        // The raw transcript should be large
        assert!(transcript.len() > MAX_TRANSCRIPT_LEN);

        // Now simulate the capping logic from run_nudge
        let capped = if transcript.len() > MAX_TRANSCRIPT_LEN {
            let mut end = MAX_TRANSCRIPT_LEN;
            while end > 0 && !transcript.is_char_boundary(end) {
                end -= 1;
            }
            format!("{}...\n\n[transcript truncated]", &transcript[..end])
        } else {
            transcript
        };

        assert!(capped.contains("[transcript truncated]"));
        // Capped length: MAX_TRANSCRIPT_LEN + "..." + "\n\n[transcript truncated]"
        assert!(capped.len() < MAX_TRANSCRIPT_LEN + 50);
    }

    // ── mock provider ────────────────────────────────────────────────

    /// A mock LLM provider that returns a preconfigured response.
    struct MockProvider {
        response: tokio::sync::Mutex<Option<MessageResponse>>,
    }

    impl MockProvider {
        fn with_response(response: MessageResponse) -> Self {
            Self {
                response: tokio::sync::Mutex::new(Some(response)),
            }
        }

        fn failing() -> Self {
            Self {
                response: tokio::sync::Mutex::new(None),
            }
        }
    }

    #[async_trait]
    impl LlmProvider for MockProvider {
        fn name(&self) -> &str {
            "mock"
        }

        fn capabilities(&self) -> ProviderCapabilities {
            ProviderCapabilities {
                streaming: false,
                tool_use: true,
                thinking: false,
                prompt_caching: false,
            }
        }

        fn cost_rates(&self, _model: &str) -> CostRates {
            CostRates {
                input_per_million: 0.0,
                output_per_million: 0.0,
                cache_read_multiplier: None,
                cache_creation_multiplier: None,
            }
        }

        async fn create_message(
            &self,
            _request: &CreateMessageRequest,
        ) -> SdkResult<MessageResponse> {
            match self.response.lock().await.take() {
                Some(r) => Ok(r),
                None => Err(agent_sdk::AgentError::Api("Mock provider failure".into())),
            }
        }

        async fn create_message_stream(
            &self,
            _request: &CreateMessageRequest,
        ) -> SdkResult<Pin<Box<dyn Stream<Item = SdkResult<StreamEvent>> + Send>>> {
            Err(agent_sdk::AgentError::Api("Not implemented".into()))
        }
    }

    fn mock_response_with_tool_calls(content: Vec<ApiContentBlock>) -> MessageResponse {
        MessageResponse {
            id: "msg_test".into(),
            role: "assistant".into(),
            content,
            model: "test-model".into(),
            stop_reason: Some("end_turn".into()),
            usage: ApiUsage {
                input_tokens: 100,
                output_tokens: 50,
                cache_creation_input_tokens: None,
                cache_read_input_tokens: None,
            },
        }
    }

    // ── run_nudge integration tests ───────────────────────────

    #[tokio::test]
    async fn nudge_executes_memory_write_tool_call() {
        let tmp = tempfile::TempDir::new().unwrap();
        let store = MemoryStore::new_user(tmp.path()).await.unwrap();
        store.write_file("MEMORY.md", "# Memory\n").await.unwrap();

        let response = mock_response_with_tool_calls(vec![ApiContentBlock::ToolUse {
            id: "tool_1".into(),
            name: "MemoryWrite".into(),
            input: serde_json::json!({
                "file": "MEMORY.md",
                "content": "\n- User prefers dark mode.",
                "append": true
            }),
        }]);

        let provider = Arc::new(MockProvider::with_response(response));
        let messages = vec![
            msg(1, "user", "I always use dark mode in my editors"),
            msg(
                2,
                "assistant",
                "Noted! I'll remember that you prefer dark mode.",
            ),
        ];

        run_nudge(provider, "test-model", &messages, &store, None, None).await;

        let content = store.read_file("MEMORY.md").unwrap();
        assert!(
            content.contains("dark mode"),
            "MemoryWrite should have persisted the preference"
        );
    }

    #[tokio::test]
    async fn nudge_executes_daily_append_tool_call() {
        let tmp = tempfile::TempDir::new().unwrap();
        let store = MemoryStore::new_user(tmp.path()).await.unwrap();

        let response = mock_response_with_tool_calls(vec![ApiContentBlock::ToolUse {
            id: "tool_1".into(),
            name: "MemoryAppendDaily".into(),
            input: serde_json::json!({
                "text": "Discussed project architecture and decided on event sourcing."
            }),
        }]);

        let provider = Arc::new(MockProvider::with_response(response));
        let messages = vec![
            msg(1, "user", "Let's use event sourcing for the new service"),
            msg(
                2,
                "assistant",
                "Good choice — event sourcing fits well here.",
            ),
        ];

        run_nudge(provider, "test-model", &messages, &store, None, None).await;

        let results = store.search("event sourcing", 5).await.unwrap();
        assert!(!results.is_empty(), "Daily log entry should be searchable");
    }

    #[tokio::test]
    async fn nudge_handles_multiple_tool_calls() {
        let tmp = tempfile::TempDir::new().unwrap();
        let store = MemoryStore::new_user(tmp.path()).await.unwrap();

        let response = mock_response_with_tool_calls(vec![
            ApiContentBlock::ToolUse {
                id: "tool_1".into(),
                name: "MemoryWrite".into(),
                input: serde_json::json!({
                    "file": "USER.md",
                    "content": "# User\n\nName: Alice\nRole: Backend engineer"
                }),
            },
            ApiContentBlock::ToolUse {
                id: "tool_2".into(),
                name: "MemoryAppendDaily".into(),
                input: serde_json::json!({
                    "text": "User introduced themselves as Alice, a backend engineer."
                }),
            },
        ]);

        let provider = Arc::new(MockProvider::with_response(response));
        let messages = vec![
            msg(1, "user", "Hey! I'm Alice, a backend engineer at Acme."),
            msg(2, "assistant", "Nice to meet you, Alice!"),
        ];

        run_nudge(provider, "test-model", &messages, &store, None, None).await;

        let user = store.read_file("USER.md").unwrap();
        assert!(user.contains("Alice"), "USER.md should contain user's name");
        assert!(
            user.contains("Backend engineer"),
            "USER.md should contain user's role"
        );

        let results = store.search("backend engineer", 5).await.unwrap();
        assert!(!results.is_empty(), "Daily log should be searchable");
    }

    #[tokio::test]
    async fn nudge_handles_nothing_to_save() {
        let tmp = tempfile::TempDir::new().unwrap();
        let store = MemoryStore::new_user(tmp.path()).await.unwrap();

        // LLM responds with text only — no tool calls
        let response = mock_response_with_tool_calls(vec![ApiContentBlock::Text {
            text: "Nothing to save".into(),
            cache_control: None,
        }]);

        let provider = Arc::new(MockProvider::with_response(response));
        let messages = vec![msg(1, "user", "Hi"), msg(2, "assistant", "Hello!")];

        // Should not panic or write anything
        run_nudge(provider, "test-model", &messages, &store, None, None).await;
    }

    #[tokio::test]
    async fn nudge_handles_provider_failure() {
        let tmp = tempfile::TempDir::new().unwrap();
        let store = MemoryStore::new_user(tmp.path()).await.unwrap();

        let provider = Arc::new(MockProvider::failing());
        let messages = vec![msg(1, "user", "Important info here")];

        // Should not panic — fail-open
        run_nudge(provider, "test-model", &messages, &store, None, None).await;
    }

    #[tokio::test]
    async fn nudge_skips_empty_transcript() {
        let tmp = tempfile::TempDir::new().unwrap();
        let store = MemoryStore::new_user(tmp.path()).await.unwrap();

        // Provider should never be called (we'll use a failing one to verify)
        let provider = Arc::new(MockProvider::failing());
        let messages: Vec<SessionMessage> = vec![];

        // Should return immediately without calling the provider
        run_nudge(provider, "test-model", &messages, &store, None, None).await;
    }

    #[tokio::test]
    async fn nudge_routes_to_user_view() {
        let agent_tmp = tempfile::TempDir::new().unwrap();
        let user_tmp = tempfile::TempDir::new().unwrap();

        let agent_store = Arc::new(MemoryStore::new_user(agent_tmp.path()).await.unwrap());
        let user_view = UserMemoryView::new(agent_store.clone(), user_tmp.path().to_path_buf())
            .await
            .unwrap();

        let response = mock_response_with_tool_calls(vec![ApiContentBlock::ToolUse {
            id: "tool_1".into(),
            name: "MemoryWrite".into(),
            input: serde_json::json!({
                "file": "USER.md",
                "content": "# User\n\nPrefers vim keybindings."
            }),
        }]);

        let provider = Arc::new(MockProvider::with_response(response));
        let messages = vec![msg(1, "user", "I use vim keybindings everywhere")];

        run_nudge(
            provider,
            "test-model",
            &messages,
            &agent_store,
            Some(&user_view),
            None,
        )
        .await;

        // The write should have gone to the user view, not the agent store
        let user_content = user_view.read_file("USER.md").unwrap();
        assert!(user_content.contains("vim keybindings"));
    }

    // ── counter / interval logic ────────────────────────────────────

    // These tests verify the counter modulo logic used by
    // StarpodAgent::maybe_nudge_memory without needing the full agent.

    /// Simulate the counter logic from `maybe_nudge_memory` and return
    /// which message numbers trigger a nudge.
    fn simulate_nudge_triggers(interval: u32, num_messages: u32) -> Vec<u32> {
        let mut counter: u32 = 0;
        let mut triggers = Vec::new();
        for msg_num in 1..=num_messages {
            counter += 1;
            if interval > 0 && counter.is_multiple_of(interval) {
                triggers.push(msg_num);
            }
        }
        triggers
    }

    #[test]
    fn counter_fires_at_exact_interval() {
        let triggers = simulate_nudge_triggers(10, 25);
        assert_eq!(triggers, vec![10, 20], "Should fire at messages 10 and 20");
    }

    #[test]
    fn counter_fires_every_message_when_interval_is_1() {
        let triggers = simulate_nudge_triggers(1, 5);
        assert_eq!(triggers, vec![1, 2, 3, 4, 5], "Should fire every message");
    }

    #[test]
    fn counter_never_fires_when_interval_is_0() {
        let triggers = simulate_nudge_triggers(0, 100);
        assert!(triggers.is_empty(), "Should never fire when disabled");
    }

    #[test]
    fn counter_fires_at_large_interval() {
        let triggers = simulate_nudge_triggers(50, 100);
        assert_eq!(triggers, vec![50, 100]);
    }

    #[test]
    fn counter_does_not_fire_before_interval() {
        let triggers = simulate_nudge_triggers(10, 9);
        assert!(
            triggers.is_empty(),
            "Should not fire before reaching interval"
        );
    }

    #[test]
    fn counter_fires_exactly_at_boundary() {
        let triggers = simulate_nudge_triggers(10, 10);
        assert_eq!(
            triggers,
            vec![10],
            "Should fire exactly at interval boundary"
        );
    }

    // ── flush_stale_sessions decision logic ─────────────────────────
    //
    // These tests verify the filter predicate used by
    // StarpodAgent::flush_stale_sessions without needing the full agent.

    /// Simulates the flush_stale_sessions filter: given a set of sessions
    /// with (user_id, count), returns which session_ids would be flushed.
    fn simulate_stale_flush(
        sessions: &[(&str, &str, u32)], // (session_id, user_id, count)
        current_session_id: &str,
        current_user_id: &str,
        interval: u32,
    ) -> Vec<String> {
        sessions
            .iter()
            .filter(|(sid, uid, count)| {
                *sid != current_session_id
                    && *uid == current_user_id
                    && *count > 0
                    && (interval == 0 || *count % interval != 0)
            })
            .map(|(sid, _, _)| sid.to_string())
            .collect()
    }

    #[test]
    fn stale_flush_finds_un_nudged_sessions_for_same_user() {
        let sessions = vec![
            ("sess-a", "alice", 3),
            ("sess-b", "alice", 7),
            ("sess-c", "bob", 5),
        ];
        let stale = simulate_stale_flush(&sessions, "sess-b", "alice", 10);
        assert_eq!(
            stale,
            vec!["sess-a"],
            "Only alice's other un-nudged session"
        );
    }

    #[test]
    fn stale_flush_skips_current_session() {
        let sessions = vec![("sess-a", "alice", 3)];
        let stale = simulate_stale_flush(&sessions, "sess-a", "alice", 10);
        assert!(stale.is_empty(), "Current session should never be flushed");
    }

    #[test]
    fn stale_flush_skips_other_users() {
        let sessions = vec![("sess-a", "bob", 3), ("sess-b", "charlie", 7)];
        let stale = simulate_stale_flush(&sessions, "sess-new", "alice", 10);
        assert!(stale.is_empty(), "Should not flush other users' sessions");
    }

    #[test]
    fn stale_flush_skips_at_interval_boundary() {
        let sessions = vec![
            ("sess-a", "alice", 10), // 10 % 10 == 0 → already nudged
            ("sess-b", "alice", 20), // 20 % 10 == 0 → already nudged
            ("sess-c", "alice", 13), // 13 % 10 != 0 → stale
        ];
        let stale = simulate_stale_flush(&sessions, "sess-new", "alice", 10);
        assert_eq!(stale, vec!["sess-c"], "Only un-nudged session should flush");
    }

    #[test]
    fn stale_flush_skips_zero_count() {
        let sessions = vec![
            ("sess-a", "alice", 0), // already flushed
        ];
        let stale = simulate_stale_flush(&sessions, "sess-new", "alice", 10);
        assert!(
            stale.is_empty(),
            "Zero-count sessions should not be flushed again"
        );
    }

    #[test]
    fn stale_flush_multiple_stale_sessions() {
        let sessions = vec![
            ("sess-a", "alice", 2),
            ("sess-b", "alice", 4),
            ("sess-c", "alice", 8),
        ];
        let stale = simulate_stale_flush(&sessions, "sess-new", "alice", 10);
        assert_eq!(stale, vec!["sess-a", "sess-b", "sess-c"]);
    }

    // ── nudge request construction ──────────────────────────────────

    #[tokio::test]
    async fn nudge_request_includes_system_prompt_and_tools() {
        // Verify the LLM request is built correctly by capturing it
        use std::sync::atomic::{AtomicBool, Ordering};

        struct InspectingProvider {
            called: AtomicBool,
        }

        #[async_trait]
        impl LlmProvider for InspectingProvider {
            fn name(&self) -> &str {
                "inspect"
            }
            fn capabilities(&self) -> ProviderCapabilities {
                ProviderCapabilities {
                    streaming: false,
                    tool_use: true,
                    thinking: false,
                    prompt_caching: false,
                }
            }
            fn cost_rates(&self, _model: &str) -> CostRates {
                CostRates {
                    input_per_million: 0.0,
                    output_per_million: 0.0,
                    cache_read_multiplier: None,
                    cache_creation_multiplier: None,
                }
            }
            async fn create_message(
                &self,
                request: &CreateMessageRequest,
            ) -> SdkResult<MessageResponse> {
                self.called.store(true, Ordering::SeqCst);

                // Verify system prompt is present
                assert!(request.system.is_some(), "System prompt should be present");
                let sys = &request.system.as_ref().unwrap()[0].text;
                assert!(
                    sys.contains("background review agent"),
                    "System prompt should identify as background review agent"
                );

                // Verify tools are present
                assert!(request.tools.is_some(), "Tools should be present");
                let tools = request.tools.as_ref().unwrap();
                assert_eq!(
                    tools.len(),
                    2,
                    "Should have MemoryWrite and MemoryAppendDaily"
                );
                assert_eq!(tools[0].name, "MemoryWrite");
                assert_eq!(tools[1].name, "MemoryAppendDaily");

                // Verify transcript is in the user message
                let user_msg = &request.messages[0];
                assert_eq!(user_msg.role, "user");
                if let ApiContentBlock::Text { text, .. } = &user_msg.content[0] {
                    assert!(
                        text.contains("dark mode"),
                        "Transcript should contain message content"
                    );
                } else {
                    panic!("Expected text content block");
                }

                // Return "nothing to save"
                Ok(MessageResponse {
                    id: "msg_test".into(),
                    role: "assistant".into(),
                    content: vec![ApiContentBlock::Text {
                        text: "Nothing to save".into(),
                        cache_control: None,
                    }],
                    model: "test".into(),
                    stop_reason: Some("end_turn".into()),
                    usage: ApiUsage {
                        input_tokens: 0,
                        output_tokens: 0,
                        cache_creation_input_tokens: None,
                        cache_read_input_tokens: None,
                    },
                })
            }
            async fn create_message_stream(
                &self,
                _request: &CreateMessageRequest,
            ) -> SdkResult<Pin<Box<dyn Stream<Item = SdkResult<StreamEvent>> + Send>>> {
                Err(agent_sdk::AgentError::Api("Not implemented".into()))
            }
        }

        let tmp = tempfile::TempDir::new().unwrap();
        let store = MemoryStore::new_user(tmp.path()).await.unwrap();
        let provider = Arc::new(InspectingProvider {
            called: AtomicBool::new(false),
        });
        let provider_dyn: Arc<dyn LlmProvider> = Arc::clone(&provider) as Arc<dyn LlmProvider>;

        let messages = vec![
            msg(1, "user", "I prefer dark mode"),
            msg(2, "assistant", "Noted!"),
        ];

        run_nudge(provider_dyn, "test-model", &messages, &store, None, None).await;
        assert!(
            provider.called.load(Ordering::SeqCst),
            "Provider should have been called"
        );
    }

    // ── config defaults and parsing ─────────────────────────────────

    #[test]
    fn nudge_system_prompt_mentions_key_file_targets() {
        assert!(NUDGE_SYSTEM_PROMPT.contains("USER.md"));
        assert!(NUDGE_SYSTEM_PROMPT.contains("MEMORY.md"));
        assert!(NUDGE_SYSTEM_PROMPT.contains("MemoryWrite"));
        assert!(NUDGE_SYSTEM_PROMPT.contains("MemoryAppendDaily"));
        assert!(NUDGE_SYSTEM_PROMPT.contains("Nothing to save"));
    }

    #[test]
    fn max_transcript_len_is_reasonable() {
        assert_eq!(MAX_TRANSCRIPT_LEN, 30_000);
        assert_eq!(MAX_MESSAGE_LEN, 1_000);
    }

    // ── self-improve / skill integration ───────────────────────────

    #[test]
    fn skill_prompt_mentions_key_tools() {
        assert!(NUDGE_SKILL_PROMPT.contains("SkillCreate"));
        assert!(NUDGE_SKILL_PROMPT.contains("SkillUpdate"));
    }

    #[test]
    fn skill_tool_definitions_has_create_and_update() {
        let tools = skill_tool_definitions();
        assert_eq!(tools.len(), 2);
        assert_eq!(tools[0].name, "SkillCreate");
        assert_eq!(tools[1].name, "SkillUpdate");
    }

    #[test]
    fn build_system_prompt_without_skills_is_base_only() {
        let prompt = build_nudge_system_prompt(None);
        assert_eq!(prompt, NUDGE_SYSTEM_PROMPT);
        assert!(!prompt.contains("SkillCreate"));
    }

    #[test]
    fn build_system_prompt_with_skills_includes_skill_guidance() {
        let tmp = tempfile::TempDir::new().unwrap();
        let store = SkillStore::new(tmp.path()).unwrap();
        let prompt = build_nudge_system_prompt(Some(&store));
        assert!(prompt.starts_with(NUDGE_SYSTEM_PROMPT));
        assert!(prompt.contains("SKILL SELF-IMPROVE"));
        assert!(prompt.contains("SkillCreate"));
        assert!(prompt.contains("SkillUpdate"));
    }

    #[test]
    fn build_system_prompt_with_existing_skills_includes_catalog() {
        let tmp = tempfile::TempDir::new().unwrap();
        let store = SkillStore::new(tmp.path()).unwrap();
        store
            .create(
                "summarize-pr",
                "Summarize a GitHub PR",
                None,
                None,
                "Steps:\n1. Read PR\n2. Summarize",
            )
            .unwrap();
        let prompt = build_nudge_system_prompt(Some(&store));
        assert!(prompt.contains("summarize-pr"));
        assert!(prompt.contains("Existing skills"));
    }

    #[test]
    fn execute_skill_tool_calls_creates_skill() {
        let tmp = tempfile::TempDir::new().unwrap();
        let store = SkillStore::new(tmp.path()).unwrap();

        let content = vec![ApiContentBlock::ToolUse {
            id: "tool_1".into(),
            name: "SkillCreate".into(),
            input: serde_json::json!({
                "name": "deploy-check",
                "description": "Verify deployment readiness",
                "body": "Steps:\n1. Run tests\n2. Check config"
            }),
        }];

        execute_skill_tool_calls(&content, &store);

        let skills = store.list().unwrap();
        assert_eq!(skills.len(), 1);
        assert_eq!(skills[0].name, "deploy-check");
    }

    #[test]
    fn execute_skill_tool_calls_updates_skill() {
        let tmp = tempfile::TempDir::new().unwrap();
        let store = SkillStore::new(tmp.path()).unwrap();
        store
            .create("deploy-check", "Old description", None, None, "Old body")
            .unwrap();

        let content = vec![ApiContentBlock::ToolUse {
            id: "tool_1".into(),
            name: "SkillUpdate".into(),
            input: serde_json::json!({
                "name": "deploy-check",
                "description": "Updated description",
                "body": "Updated body"
            }),
        }];

        execute_skill_tool_calls(&content, &store);

        let skills = store.list().unwrap();
        assert_eq!(skills[0].description, "Updated description");
    }

    #[test]
    fn execute_skill_tool_calls_ignores_memory_tools() {
        let tmp = tempfile::TempDir::new().unwrap();
        let store = SkillStore::new(tmp.path()).unwrap();

        let content = vec![
            ApiContentBlock::ToolUse {
                id: "tool_1".into(),
                name: "MemoryWrite".into(),
                input: serde_json::json!({"file": "MEMORY.md", "content": "test"}),
            },
            ApiContentBlock::ToolUse {
                id: "tool_2".into(),
                name: "MemoryAppendDaily".into(),
                input: serde_json::json!({"text": "test"}),
            },
        ];

        // Should not panic — memory tools are silently skipped
        execute_skill_tool_calls(&content, &store);
        assert!(store.list().unwrap().is_empty());
    }

    #[tokio::test]
    async fn nudge_executes_skill_create_when_skills_provided() {
        let mem_tmp = tempfile::TempDir::new().unwrap();
        let skill_tmp = tempfile::TempDir::new().unwrap();
        let mem_store = MemoryStore::new_user(mem_tmp.path()).await.unwrap();
        let skill_store = SkillStore::new(skill_tmp.path()).unwrap();

        let response = mock_response_with_tool_calls(vec![ApiContentBlock::ToolUse {
            id: "tool_1".into(),
            name: "SkillCreate".into(),
            input: serde_json::json!({
                "name": "debug-crash",
                "description": "Debug application crashes",
                "body": "1. Check logs\n2. Reproduce\n3. Fix"
            }),
        }]);

        let provider = Arc::new(MockProvider::with_response(response));
        let messages = vec![
            msg(1, "user", "The app keeps crashing on startup"),
            msg(
                2,
                "assistant",
                "I found the issue — a null pointer in init().",
            ),
            msg(3, "user", "Thanks, that fixed it!"),
        ];

        run_nudge(
            provider,
            "test-model",
            &messages,
            &mem_store,
            None,
            Some(&skill_store),
        )
        .await;

        let skills = skill_store.list().unwrap();
        assert_eq!(skills.len(), 1);
        assert_eq!(skills[0].name, "debug-crash");
    }

    #[tokio::test]
    async fn nudge_handles_mixed_memory_and_skill_calls() {
        let mem_tmp = tempfile::TempDir::new().unwrap();
        let skill_tmp = tempfile::TempDir::new().unwrap();
        let mem_store = MemoryStore::new_user(mem_tmp.path()).await.unwrap();
        mem_store
            .write_file("MEMORY.md", "# Memory\n")
            .await
            .unwrap();
        let skill_store = SkillStore::new(skill_tmp.path()).unwrap();

        let response = mock_response_with_tool_calls(vec![
            ApiContentBlock::ToolUse {
                id: "tool_1".into(),
                name: "MemoryWrite".into(),
                input: serde_json::json!({
                    "file": "MEMORY.md",
                    "content": "\n- User prefers monorepo structure.",
                    "append": true
                }),
            },
            ApiContentBlock::ToolUse {
                id: "tool_2".into(),
                name: "SkillCreate".into(),
                input: serde_json::json!({
                    "name": "setup-monorepo",
                    "description": "Set up a Rust workspace monorepo",
                    "body": "1. Create workspace Cargo.toml\n2. Add crates"
                }),
            },
        ]);

        let provider = Arc::new(MockProvider::with_response(response));
        let messages = vec![
            msg(1, "user", "Help me set up a monorepo"),
            msg(2, "assistant", "Done! Created workspace with 3 crates."),
        ];

        run_nudge(
            provider,
            "test-model",
            &messages,
            &mem_store,
            None,
            Some(&skill_store),
        )
        .await;

        // Memory was written
        let memory = mem_store.read_file("MEMORY.md").unwrap();
        assert!(memory.contains("monorepo"));

        // Skill was created
        let skills = skill_store.list().unwrap();
        assert_eq!(skills.len(), 1);
        assert_eq!(skills[0].name, "setup-monorepo");
    }

    #[tokio::test]
    async fn nudge_skips_skills_when_none() {
        let mem_tmp = tempfile::TempDir::new().unwrap();
        let mem_store = MemoryStore::new_user(mem_tmp.path()).await.unwrap();

        // Response includes a SkillCreate call, but skills is None
        let response = mock_response_with_tool_calls(vec![ApiContentBlock::ToolUse {
            id: "tool_1".into(),
            name: "SkillCreate".into(),
            input: serde_json::json!({
                "name": "should-not-exist",
                "description": "This should not be created",
                "body": "nope"
            }),
        }]);

        let provider = Arc::new(MockProvider::with_response(response));
        let messages = vec![msg(1, "user", "test")];

        // skills = None, so SkillCreate should be ignored
        run_nudge(provider, "test-model", &messages, &mem_store, None, None).await;

        // No way to verify skill wasn't created without a store — but no panic is the key check
    }
}