iron-core 0.1.37

//! Handoff export/import for session continuity.
//!
//! The handoff bundle transfers conversation state (messages, instructions,
//! compacted context) but explicitly EXCLUDES:
//! - Runtime-local tool capabilities (including MCP server inventory)
//! - Runtime-local capability configurations
//! - Session MCP enablement state
//! - Session plugin enablement state and plugin auth bindings
//! - Other runtime-local state that may differ between environments
//!
//! This preserves portability: the destination runtime determines its own
//! available integrations and tools.

use crate::context::config::ContextManagementConfig;
use crate::context::model_switch::ModelSwitchRecord;
use crate::context::models::CompressedBlock;
use crate::durable::{DurableSession, SessionId, StructuredMessage};
use crate::skill::SessionSkillState;
use serde::{Deserialize, Serialize};

/// Current serialized handoff bundle format version.
pub const HANDOFF_BUNDLE_VERSION: &str = "1";

/// Provenance and approximate size of a handoff bundle.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct HandoffBundleMetadata {
    /// Metadata schema version.
    pub version: String,
    /// Model reported by the exporter.
    pub source_model: String,
    /// Source provider name, when known.
    pub source_provider: Option<String>,
    /// Display form of the source session identifier.
    pub source_session_id: String,
    /// Heuristic size of instructions, summaries, tail, and active skills.
    pub size_estimate_tokens: usize,
}

/// Portable continuity state transferred between durable sessions.
///
/// The bundle owns cloned instructions, summaries, recent messages, skill
/// state, profile snapshots, and model-switch state. Runtime-local MCP and
/// plugin enablement are intentionally absent. Managed provider credentials
/// are included when present, so serialized bundles must be handled as secrets.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct HandoffBundle {
    /// Bundle schema version.
    pub version: String,
    /// Explicit source-session instructions.
    pub instructions: Option<String>,
    /// Human-readable continuity and portability note.
    pub handoff_note: String,
    /// Durable summaries selected for transfer.
    pub compressed_blocks: Vec<CompressedBlock>,
    /// Recent structured messages selected for transfer.
    pub recent_tail: Vec<StructuredMessage>,
    /// Activated skill state preserved across runtimes.
    pub skill_state: SessionSkillState,
    /// Bundle provenance and size estimate.
    pub metadata: HandoffBundleMetadata,
    /// Model-switch history preserved across handoffs.
    pub model_switch_history: Vec<ModelSwitchRecord>,
    /// Current model after the most recent switch.
    pub current_model: Option<String>,
    /// Current managed-provider slug, if any.
    pub current_provider_slug: Option<String>,
    /// Current managed-provider API key, if any.
    ///
    /// Wrapped in a [`crate::secret::SecretString`] so the credential is redacted
    /// from debug output. It still serializes transparently because serialized
    /// bundles must remain usable as portable secrets.
    pub current_provider_api_key: Option<crate::secret::SecretString>,
    /// Profile identity prompt selected for this session, if any.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub profile_identity: Option<String>,
    /// Tools hidden due to model capability differences.
    #[serde(default)]
    pub hidden_tools: Vec<String>,
    /// The profile id last used for this session, if any.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub profile_id: Option<crate::profile::AgentProfileId>,
    /// Session-effective snapshot of the profile's tool filter at setup time.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub effective_tool_filter: Option<crate::profile::ToolFilter>,
    /// Session-effective snapshot of the profile's approval posture at setup time.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub effective_approval: Option<crate::profile::AgentApproval>,
    /// Session-effective snapshot of the resolved model at setup time.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub effective_model: Option<String>,
    /// Whether the session was created with a profile that is no longer available.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub profile_unavailable: Option<String>,
    /// Session-effective snapshot of the resolved provider context at setup time.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub effective_provider_context:
        Option<crate::provider_credential::domain::ProviderPromptContext>,
}

/// Validator and builder for portable handoff bundles.
pub struct HandoffExporter;

impl HandoffExporter {
    /// Returns whether the session has no pending or running tool calls.
    ///
    /// Handoff export is restricted to this idle tool lifecycle boundary.
    pub fn can_export(session: &DurableSession) -> bool {
        !session.tool_records.iter().any(|r| {
            matches!(
                r.status,
                crate::durable::ToolRecordStatus::PendingApproval
                    | crate::durable::ToolRecordStatus::Running
            )
        })
    }

    /// Clones selected continuity state into a portable bundle.
    ///
    /// `compressed_blocks` and `tail` are caller-selected views; they need not
    /// equal all context currently owned by `session`. Runtime-local tool and
    /// plugin enablement are not exported.
    ///
    /// # Errors
    ///
    /// Returns an error while a tool call is pending approval or running.
    pub fn export(
        session: &DurableSession,
        model: &str,
        compressed_blocks: &[CompressedBlock],
        tail: Vec<StructuredMessage>,
        config: &ContextManagementConfig,
        provider_name: Option<&str>,
    ) -> Result<HandoffBundle, String> {
        if !Self::can_export(session) {
            return Err("Cannot export handoff bundle: session has active tool calls".into());
        }

        let target_tokens = config.handoff_export.default_target_tokens;
        let size_estimate = estimate_bundle_size(
            compressed_blocks,
            &tail,
            session.instruction_text_for_estimate().as_deref(),
            &session.skill_state,
        );

        let mut handoff_note = format!(
            "Context transferred from session {} on model {}.",
            session.id, model
        );

        let mut loss_notes = Vec::new();
        for msg in &tail {
            for block in msg.content_blocks().iter() {
                if let crate::durable::ContentBlock::Resource { uri, .. } = block {
                    if is_local_resource(uri.as_str()) {
                        loss_notes.push(format!(
                            "Local resource '{}' may not be accessible at destination",
                            uri
                        ));
                    }
                }
            }
        }

        if !loss_notes.is_empty() {
            handoff_note.push_str(&format!("\nPortability notes: {}", loss_notes.join("; ")));
        }

        if size_estimate > target_tokens {
            handoff_note.push_str(&format!(
                "\nBundle size (~{} tokens) exceeds target (~{} tokens).",
                size_estimate, target_tokens
            ));
        }

        let mut bundle = HandoffBundle {
            version: HANDOFF_BUNDLE_VERSION.to_string(),
            instructions: session.instructions.clone(),
            handoff_note,
            compressed_blocks: compressed_blocks.to_vec(),
            recent_tail: tail,
            skill_state: session.skill_state.clone(),
            metadata: HandoffBundleMetadata {
                version: HANDOFF_BUNDLE_VERSION.to_string(),
                source_model: model.to_string(),
                source_provider: provider_name.map(|s| s.to_string()),
                source_session_id: session.id.to_string(),
                size_estimate_tokens: size_estimate,
            },
            model_switch_history: session.model_switch_history.clone(),
            current_model: session.current_model.clone(),
            current_provider_slug: session.current_provider_slug.clone(),
            current_provider_api_key: session.current_provider_api_key.clone(),
            profile_identity: session.profile_identity.clone(),
            hidden_tools: session.hidden_tools.clone(),
            profile_id: session.profile_id.clone(),
            effective_tool_filter: session.effective_tool_filter.clone(),
            effective_approval: session.effective_approval,
            effective_model: session.effective_model.clone(),
            profile_unavailable: session.profile_unavailable.clone(),
            effective_provider_context: session.effective_provider_context.clone(),
        };

        if config.handoff_export.include_portability_notes && !loss_notes.is_empty() {
            // Portability notes are no longer stored in a structured compacted_context.
            // They are appended to the handoff_note instead.
            for note in loss_notes {
                bundle
                    .handoff_note
                    .push_str(&format!("\nPortability note: {}", note));
            }
        }

        Ok(bundle)
    }
}

/// Hydrates durable sessions from owned handoff bundles.
pub struct HandoffImporter;

impl HandoffImporter {
    /// Merges an owned bundle into an existing durable session.
    ///
    /// Imported summaries are rendered as an agent message, recent tail items
    /// are appended directly to message storage, and model-switch timeline
    /// metadata is recreated. Existing runtime-local MCP and plugin enablement
    /// remains owned by the target and is not replaced. The target retains its
    /// session identity.
    ///
    /// # Errors
    ///
    /// Returns an error if the target identifier equals the newly allocated
    /// identity used by the method's mismatch guard.
    pub fn hydrate(target: &mut DurableSession, bundle: HandoffBundle) -> Result<(), String> {
        if target.id == SessionId::new() {
            return Err(
                "Cannot hydrate into a freshly-constructed session with mismatched identity".into(),
            );
        }

        if !bundle.handoff_note.is_empty() {
            target.add_agent_text(format!("[Handoff] {}", bundle.handoff_note));
        }

        if let Some(instr) = bundle.instructions {
            target.set_instructions(instr);
        }

        if let Some(identity) = bundle.profile_identity {
            target.set_profile_identity(identity);
        }

        if !bundle.compressed_blocks.is_empty() {
            let rendered = bundle
                .compressed_blocks
                .iter()
                .map(|b| b.render_to_text())
                .collect::<Vec<_>>()
                .join("\n");
            if !rendered.is_empty() {
                target.add_agent_text(format!("[Compressed context]\n{}", rendered));
            }
        }

        for msg in bundle.recent_tail {
            target.messages.push(msg);
        }

        // Restore skill state so activated skills survive handoff
        target.skill_state = bundle.skill_state;

        // Restore model switch history and capability restrictions
        target.model_switch_history = bundle.model_switch_history.clone();
        target.current_model = bundle.current_model.clone();
        target.current_provider_slug = bundle.current_provider_slug.clone();
        target.current_provider_api_key = bundle.current_provider_api_key.clone();
        target.hidden_tools = bundle.hidden_tools.clone();
        target.profile_id = bundle.profile_id.clone();
        target.effective_tool_filter = bundle.effective_tool_filter.clone();
        target.effective_approval = bundle.effective_approval;
        target.effective_model = bundle.effective_model.clone();
        target.profile_unavailable = bundle.profile_unavailable.clone();
        target.effective_provider_context = bundle.effective_provider_context.clone();

        // Recreate timeline entries from model switch history
        for record in &bundle.model_switch_history {
            let timeline_index = target.timeline.len() as u64;
            target
                .timeline
                .push(crate::durable::TimelineEntry::ModelSwitched {
                    index: timeline_index,
                    from_model: record.from_model.clone(),
                    to_model: record.to_model.clone(),
                    from_provider: record.from_provider.clone(),
                    to_provider: record.to_provider.clone(),
                    adapted: record.adapted,
                    visible_id: None,
                });
        }

        // Note: MCP server and plugin enablement are NOT imported as part of handoff.
        // The destination runtime determines its own tool availability.

        Ok(())
    }

    /// Creates a fresh durable session and hydrates it from an owned bundle.
    ///
    /// The destination receives a new [`SessionId`]. Runtime-local MCP and
    /// plugin enablement starts empty rather than crossing the handoff boundary.
    pub fn hydrate_into_new(bundle: HandoffBundle) -> DurableSession {
        let mut session = DurableSession::new(SessionId::new());

        if let Some(instr) = bundle.instructions {
            session.set_instructions(instr);
        }

        if let Some(identity) = bundle.profile_identity {
            session.set_profile_identity(identity);
        }

        if !bundle.handoff_note.is_empty() {
            session.add_agent_text(format!("[Handoff] {}", bundle.handoff_note));
        }

        if !bundle.compressed_blocks.is_empty() {
            let rendered = bundle
                .compressed_blocks
                .iter()
                .map(|b| b.render_to_text())
                .collect::<Vec<_>>()
                .join("\n");
            if !rendered.is_empty() {
                session.add_agent_text(format!("[Compressed context]\n{}", rendered));
            }
        }

        for msg in bundle.recent_tail {
            session.messages.push(msg);
        }

        // Restore skill state so activated skills survive handoff
        session.skill_state = bundle.skill_state;

        // Restore model switch history and capability restrictions
        session.model_switch_history = bundle.model_switch_history.clone();
        session.current_model = bundle.current_model.clone();
        session.current_provider_slug = bundle.current_provider_slug.clone();
        session.current_provider_api_key = bundle.current_provider_api_key.clone();
        session.hidden_tools = bundle.hidden_tools.clone();
        session.profile_id = bundle.profile_id.clone();
        session.effective_tool_filter = bundle.effective_tool_filter.clone();
        session.effective_approval = bundle.effective_approval;
        session.effective_model = bundle.effective_model.clone();
        session.profile_unavailable = bundle.profile_unavailable.clone();
        session.effective_provider_context = bundle.effective_provider_context.clone();

        // Recreate timeline entries from model switch history
        for record in &bundle.model_switch_history {
            let timeline_index = session.timeline.len() as u64;
            session
                .timeline
                .push(crate::durable::TimelineEntry::ModelSwitched {
                    index: timeline_index,
                    from_model: record.from_model.clone(),
                    to_model: record.to_model.clone(),
                    from_provider: record.from_provider.clone(),
                    to_provider: record.to_provider.clone(),
                    adapted: record.adapted,
                    visible_id: None,
                });
        }

        // Note: MCP server and plugin enablement are NOT imported as part of handoff.
        // The destination runtime determines its own tool availability.

        session
    }
}

fn estimate_bundle_size(
    compressed_blocks: &[CompressedBlock],
    tail: &[StructuredMessage],
    instructions: Option<&str>,
    skill_state: &SessionSkillState,
) -> usize {
    let mut total = 0usize;
    if let Some(instr) = instructions {
        total += (instr.len() as f64 * 0.25).ceil() as usize;
    }
    for block in compressed_blocks {
        total += (block.render_to_text().len() as f64 * 0.25).ceil() as usize;
    }
    for msg in tail {
        total += (msg.text_content().len() as f64 * 0.25).ceil() as usize;
    }
    // Include activated skill instructions in size estimate
    let skill_instructions = skill_state.active_skill_instructions();
    if !skill_instructions.is_empty() {
        total += (skill_instructions.len() as f64 * 0.25).ceil() as usize;
    }
    total
}

fn is_local_resource(uri: &str) -> bool {
    uri.starts_with("file://")
        || uri.starts_with("localhost")
        || uri.starts_with("127.0.0.1")
        || uri.starts_with("unix://")
        || uri.starts_with("/dev/")
}

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

    /// Verifies that `hydrate_into_new` does **not** carry over plugin
    /// enablement state from the source session.  The destination runtime
    /// must determine its own tool availability.
    #[test]
    fn hydrate_into_new_produces_empty_plugin_enablement() {
        // Create a source session with plugin enablement state.
        let mut source = DurableSession::new(SessionId::new());
        source.set_plugin_enabled("plugin-a", true);
        source.set_plugin_enabled("plugin-b", false);
        assert_eq!(
            source.list_enabled_plugins(),
            vec!["plugin-a".to_string()],
            "sanity check: source should have plugin-a enabled"
        );

        // Export a handoff bundle (minimal — no messages needed).
        let config = ContextManagementConfig::default();
        let bundle = HandoffExporter::export(&source, "test-model", &[], vec![], &config, None)
            .expect("export should succeed for idle session");

        // Hydrate into a new session.
        let hydrated = HandoffImporter::hydrate_into_new(bundle);

        // The hydrated session must have empty plugin enablement.
        assert!(
            hydrated.list_enabled_plugins().is_empty(),
            "plugin enablement must not survive handoff; got {:?}",
            hydrated.list_enabled_plugins()
        );
        assert_eq!(
            hydrated.is_plugin_enabled("plugin-a"),
            None,
            "plugin-a must have no explicit enablement after hydration"
        );
        assert_eq!(
            hydrated.is_plugin_enabled("plugin-b"),
            None,
            "plugin-b must have no explicit enablement after hydration"
        );
    }

    /// Verifies that the `hydrate` (in-place) path also excludes plugin
    /// enablement — the import path never touches plugin_enablement.
    #[test]
    fn hydrate_in_place_does_not_modify_plugin_enablement() {
        let mut source = DurableSession::new(SessionId::new());
        source.set_plugin_enabled("plugin-x", true);
        source.add_agent_text("hello");

        let config = ContextManagementConfig::default();
        let bundle = HandoffExporter::export(&source, "test-model", &[], vec![], &config, None)
            .expect("export should succeed");

        // Create a target with its own plugin enablement.
        let mut target = DurableSession::new(SessionId::new());
        target.set_plugin_enabled("plugin-y", true);

        HandoffImporter::hydrate(&mut target, bundle).expect("hydrate should succeed");

        // Target must retain its own enablement; nothing from source imported.
        assert_eq!(
            target.is_plugin_enabled("plugin-x"),
            None,
            "source plugin enablement must not leak into target"
        );
        assert_eq!(
            target.is_plugin_enabled("plugin-y"),
            Some(true),
            "target's own plugin enablement must be preserved"
        );
    }

    #[test]
    fn handoff_preserves_activated_skills() {
        let mut source = DurableSession::new(SessionId::new());
        source.activate_skill("test-skill", "# Test Skill\nDo something useful.", vec![]);
        source.add_agent_text("hello");

        assert!(source.skill_state.is_active("test-skill"));

        let config = ContextManagementConfig::default();
        let bundle = HandoffExporter::export(&source, "test-model", &[], vec![], &config, None)
            .expect("export should succeed");

        // Verify skill state is in the bundle
        assert!(bundle.skill_state.is_active("test-skill"));
        assert_eq!(bundle.skill_state.active.len(), 1);
        assert_eq!(bundle.skill_state.active[0].name, "test-skill");
        assert_eq!(
            bundle.skill_state.active[0].body,
            "# Test Skill\nDo something useful."
        );

        // Hydrate into a new session
        let hydrated = HandoffImporter::hydrate_into_new(bundle);

        // Skill state should survive handoff
        assert!(hydrated.skill_state.is_active("test-skill"));
        assert_eq!(hydrated.skill_state.active.len(), 1);
        assert_eq!(
            hydrated.active_skill_instructions(),
            "<skill_content name=\"test-skill\">\n# Test Skill\nDo something useful.\n</skill_content>"
        );
    }

    #[test]
    fn handoff_includes_skill_state_in_size_estimate() {
        let mut source = DurableSession::new(SessionId::new());
        source.activate_skill("big-skill", "x".repeat(1000), vec![]);

        let config = ContextManagementConfig::default();
        let bundle = HandoffExporter::export(&source, "test-model", &[], vec![], &config, None)
            .expect("export should succeed");

        // Size estimate should include skill instructions (~250 tokens for 1000 chars)
        assert!(
            bundle.metadata.size_estimate_tokens >= 250,
            "Size estimate should include skill instructions, got {} tokens",
            bundle.metadata.size_estimate_tokens
        );
    }
}