basis 0.2.0

//! Building the process-scoped substrate: everything that changes when the
//! host changes, and nothing that changes when a repository does.
//!
//! ADR-0018 moved these knobs off [`WorkspaceBuilder`](crate::WorkspaceBuilder):
//! the provider, the credential, the base URL, the history store policy, the
//! host's interceptors — plus the command environment, which the ADR's list
//! does not name but which is executor infrastructure and therefore fixed at
//! the same time everything else on a mentra runtime is. What stays on the
//! workspace is what the repository says.

use std::{
    collections::BTreeMap,
    path::{Path, PathBuf},
    sync::Arc,
};
#[cfg(feature = "mcp")]
use std::{collections::HashMap, sync::Mutex};

use mentra::{
    BuiltinProvider, ModelSelector, ProviderId, RuntimePolicy,
    provider_core::{StaticCredentialSource, responses, responses::ResponsesProvider},
};

use crate::{
    approval::ApprovalGate, hooks::Interceptor, provider, run::RunError, shell::ShellAccess, store,
    tools::SpawnTool,
};

use super::{
    Runtime,
    dispatch::{DispatchHook, HookDispatch},
    environment::EnvironmentExecutor,
};

/// The persist tag a shared runtime's own conversations carry until mentra can
/// tag per session (see [`Runtime::mint`]). Never a workspace's tag — those
/// come from [`store::runtime_identifier`] — so shared-path rows written under
/// it stay out of every per-workspace list rather than leaking into one.
const SHARED_IDENTIFIER: &str = "basis:runtime";

/// How a runtime is built.
///
/// Named a builder because it is one: filled in, then consumed by
/// [`build`](Self::build) — or embedded in a
/// [`WorkspaceBuilder`](crate::WorkspaceBuilder) via
/// [`with_runtime_builder`](crate::WorkspaceBuilder::with_runtime_builder),
/// where [`Workspace::open`](crate::Workspace::open) builds it bound to the
/// workspace's own path. Fields are private because one of them is a
/// credential. `with_*` returns a new value, so a host can keep a
/// half-configured builder and finish it differently per runtime.
pub struct RuntimeBuilder {
    provider: Option<BuiltinProvider>,
    base_url: Option<String>,
    api_key: Option<String>,
    model: ModelSelector,
    history: Option<History>,
    interceptors: Vec<Arc<dyn Interceptor>>,
    command_environment: BTreeMap<String, String>,
}

/// What a caller said about where this runtime's conversations go.
///
/// One field rather than a directory beside a flag, so that the two knobs which
/// set it cannot both be in force: whichever was called last is the one that is
/// read, and there is no state in which they disagree. `None` is *unsaid* —
/// mentra chooses, which is neither of these.
#[derive(Debug, Clone, PartialEq, Eq)]
pub(crate) enum History {
    /// [`RuntimeBuilder::with_store_dir`]: kept in this directory.
    Directory(PathBuf),
    /// [`RuntimeBuilder::with_ephemeral_history`]: kept in memory, and
    /// nowhere else.
    Ephemeral,
}

/// Hand-written so a supplied credential cannot reach a log through a
/// `{:?}`. Everything else is printed as it is; the command environment names
/// its variables and redacts their values.
impl std::fmt::Debug for RuntimeBuilder {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("RuntimeBuilder")
            .field("provider", &self.provider)
            .field("base_url", &self.base_url)
            .field("api_key", &self.api_key.as_ref().map(|_| "<redacted>"))
            .field("model", &self.model)
            .field("history", &self.history)
            .field(
                "interceptors",
                &self
                    .interceptors
                    .iter()
                    .map(|interceptor| interceptor.name())
                    .collect::<Vec<_>>(),
            )
            .field(
                "command_environment",
                &self.command_environment.keys().collect::<Vec<_>>(),
            )
            .finish()
    }
}

impl Default for RuntimeBuilder {
    fn default() -> Self {
        Self {
            provider: None,
            base_url: None,
            api_key: None,
            model: ModelSelector::NewestAvailable,
            history: None,
            interceptors: Vec::new(),
            command_environment: BTreeMap::new(),
        }
    }
}

impl RuntimeBuilder {
    pub fn with_provider(self, provider: BuiltinProvider) -> Self {
        Self {
            provider: Some(provider),
            ..self
        }
    }

    /// Points the runtime at an OpenAI-compatible endpoint. A trailing `/v1`
    /// is stripped during resolution — paste the URL a gateway publishes.
    /// Compatible endpoints use complete local replay rather than automatic
    /// `previous_response_id` chaining.
    pub fn with_base_url(self, base_url: impl Into<String>) -> Self {
        Self {
            base_url: Some(base_url.into()),
            ..self
        }
    }

    /// Supplies the provider credential directly, instead of having basis read it
    /// from the environment.
    ///
    /// A host whose key lives in a vault, a keychain, or a token it just
    /// exchanged should not have to export an environment variable for basis to
    /// find it again. Unset by default, which is the behavior every existing
    /// caller has: the key is looked up by the variable names the ecosystem
    /// already uses (see [`crate::provider`]).
    ///
    /// A key with no [`with_provider`](Self::with_provider) and no
    /// [`with_base_url`](Self::with_base_url) is refused rather than guessed
    /// at — with nothing to attribute it to, basis would be picking a service to
    /// send someone's credential to.
    pub fn with_api_key(self, api_key: impl Into<String>) -> Self {
        Self {
            api_key: Some(api_key.into()),
            ..self
        }
    }

    /// Sets the model resolution *policy*: what every workspace on this runtime
    /// resolves unless it overrides with
    /// [`WorkspaceBuilder::with_model`](crate::WorkspaceBuilder::with_model).
    ///
    /// A policy rather than a resolved model, because resolution needs the
    /// provider and may need the network, and both are workspace-open facts:
    /// the resolved id stays a [`Workspace`](crate::Workspace) fact (ADR-0018).
    pub fn with_model(self, model: ModelSelector) -> Self {
        Self { model, ..self }
    }

    /// Keeps this runtime's conversations in `dir` rather than in the
    /// machine-wide default.
    ///
    /// Unset, mentra chooses, and what it chooses is keyed by the **process's
    /// current directory** rather than by any workspace basis opened — so a host
    /// that opens two workspaces from one place writes both histories to one
    /// file, and a test suite writes to a real database under the user's data
    /// directory whatever temp directory it opened. Two callers want to say
    /// otherwise: a host that keeps basis's history inside its own application
    /// data, and a test that wants no persistent side effect at all. Both are
    /// asking the same question — *where* — so that is what this takes.
    /// [`with_ephemeral_history`](Self::with_ephemeral_history) answers it with
    /// *nowhere*, and is the last word between the two: whichever was called
    /// last decides.
    ///
    /// Not the store itself, though mentra's `RuntimeBuilder::with_store` would
    /// take one. `RuntimeStore` is a composition of nine traits, and under the
    /// rule written on [`CancellationToken`](crate::CancellationToken) — every
    /// mentra type basis's surface makes a caller *name*, basis re-exports — that
    /// shape would cost the re-export of all nine plus the record types they
    /// pass. What it would buy is reachable without it: mentra ships two
    /// stores, a SQLite file and an in-memory one, and between this and
    /// [`with_ephemeral_history`](Self::with_ephemeral_history) a caller
    /// already picks either without naming a mentra type. A caller that
    /// genuinely wants its own backend still has one, on
    /// [`Runtime::mentra_runtime`]'s side of the bargain: build the mentra
    /// runtime and drive it directly.
    ///
    /// The directory is created on first write, and basis names the file inside
    /// it — [`store::list_in`](crate::store::list_in) is how the same
    /// conversations are read back, and it has to be able to find them.
    /// Pointing this at [`store::default_directory`](crate::store::default_directory)
    /// is exactly the default.
    ///
    /// Deliberately absent from [`RunConfig`](crate::RunConfig), for the reason
    /// its `api_key` is: a one-prompt config describes an invocation, and where
    /// a machine keeps its history is not something an invocation decides. A
    /// one-shot caller that needs it hands
    /// [`RunConfig::split`](crate::RunConfig::split)'s builder a runtime recipe
    /// through [`WorkspaceBuilder::with_runtime_builder`](crate::WorkspaceBuilder::with_runtime_builder),
    /// which is the documented migration path.
    pub fn with_store_dir(self, dir: impl Into<PathBuf>) -> Self {
        Self {
            history: Some(History::Directory(dir.into())),
            ..self
        }
    }

    /// Keeps this runtime's conversations in memory, and nowhere else.
    ///
    /// The sibling of [`with_store_dir`](Self::with_store_dir), for the caller
    /// whose answer to *where* is *nowhere*. mentra's in-memory store backs it:
    /// no database file is opened, no transcript snapshot is written, no
    /// directory is created, and dropping the [`Runtime`] takes the history
    /// with it.
    ///
    /// **Nothing survives the process.** While the runtime lives a conversation
    /// behaves as it always does — [`Workspace::resume`](crate::Workspace::resume)
    /// finds an agent this runtime minted, because the store lives exactly as
    /// long as the runtime does. Past that edge there is nothing to find: a
    /// later process cannot resume one of these by agent id, a second runtime
    /// gets its own empty store, and
    /// [`store::list_in`](crate::store::list_in) has no file to read whichever
    /// directory it is pointed at, so `session/list` over ACP reports nothing.
    /// There is no flush and no export — a host that might want a transcript
    /// later wants [`with_store_dir`](Self::with_store_dir) now.
    ///
    /// Who asks for it. A test suite, which otherwise writes to the real
    /// database under the user's data directory. And a host whose conversations
    /// are genuinely disposable — a request-scoped run inside a server, a
    /// one-shot classifier — where keeping a transcript is a cost and a
    /// disclosure rather than a feature.
    ///
    /// Setting this and [`with_store_dir`](Self::with_store_dir) is not an
    /// error: they write one field, so the last call wins — the same rule as
    /// every single-valued knob on this builder, and what makes the
    /// half-configured builder this type advertises usable.
    pub fn with_ephemeral_history(self) -> Self {
        Self {
            history: Some(History::Ephemeral),
            ..self
        }
    }

    /// Gives the host's own code a say over each tool call, on every workspace
    /// this runtime carries.
    ///
    /// The in-process binding of ADR-0012's interception contract, and the
    /// sibling of [`WorkspaceBuilder::with_hooks`](crate::WorkspaceBuilder::with_hooks):
    /// same vocabulary — allow, deny with a reason, modify with a replacement
    /// input — and the same chain. What it buys is the case a subprocess
    /// answers badly, because the judgement needs something the embedding
    /// program is already holding: the vault handle, the token it just
    /// exchanged, the policy it parsed at startup. Redacting a credential out
    /// of a tool's input is the worked example.
    ///
    /// Runtime-scoped because host scope *is* runtime scope (ADR-0018): the
    /// chain has always run host interceptors → global hooks → workspace
    /// hooks, and this is the registration point that matches the first slot.
    /// Appends, so a host may register several; they are consulted in the
    /// order registered, and **before** any subprocess hook. The rule is that
    /// the further a participant is from the workspace's own data, the earlier
    /// it speaks — an interceptor is compiled into this program, while
    /// `.basis/hooks.json` came with a repository — and since the first refusal
    /// short-circuits, that is what lets the host's own guard stop a
    /// repository's program from being spawned at all. It is not a claim of
    /// precedence: a hook still sees, and can still refuse, whatever an
    /// interceptor rewrote.
    ///
    /// Fail-closed carries over unchanged: an interceptor that returns an error
    /// or panics denies the call, and says which one it was.
    pub fn with_interceptor(self, interceptor: impl Interceptor + 'static) -> Self {
        Self {
            interceptors: {
                let mut interceptors = self.interceptors;
                interceptors.push(Arc::new(interceptor));
                interceptors
            },
            ..self
        }
    }

    /// Adds one fixed environment value to every command this runtime runs.
    ///
    /// Mentra clears the ambient environment, so a host must state execution
    /// context explicitly. A later call with the same name replaces the
    /// earlier value. Debug output names variables but redacts values.
    ///
    /// Runtime-scoped, so on a shared runtime every workspace's commands see
    /// the same pairs. A host that wants two concurrently driven workspaces to
    /// carry different identities gives each its own runtime through
    /// [`WorkspaceBuilder::with_runtime_builder`](crate::WorkspaceBuilder::with_runtime_builder),
    /// which is what the local task service does.
    pub fn with_command_environment(
        mut self,
        name: impl Into<String>,
        value: impl Into<String>,
    ) -> Self {
        self.command_environment.insert(name.into(), value.into());
        self
    }

    /// Builds the workspace-agnostic runtime: the substrate an N-repository
    /// host hands to every [`WorkspaceBuilder::with_runtime`](crate::WorkspaceBuilder::with_runtime).
    ///
    /// Synchronous, and deliberately so: nothing here needs the network. The
    /// provider is resolved (credential lookup, no request), the mentra
    /// runtime is assembled, and that is all — MCP servers are a workspace
    /// concern and are connected by [`Workspace::open`](crate::Workspace::open),
    /// never here.
    ///
    /// Per-workspace file confinement needs no policy roots: mentra's builtin
    /// file tools always allow paths under the calling agent's own `base_dir`,
    /// which basis sets per workspace. What this policy grants is command
    /// execution — shell and background on, workspace-bounded's timeouts — and
    /// a workspace that says [`ShellAccess::Denied`] is enforced per-workspace
    /// by the runtime's hook dispatcher instead of by this shared policy.
    pub fn build(self) -> Result<Runtime, RunError> {
        self.build_with(SHARED_IDENTIFIER.to_string(), shared_policy())
    }

    /// The sugar path: the same build, bound to one workspace.
    ///
    /// What `Workspace::open(path)` has always done, byte for byte — the
    /// per-path persist identifier, `git_protected(workspace_bounded(path))`,
    /// the caller's shell posture baked into policy as a second belt beside
    /// the dispatcher's guard.
    pub(crate) fn build_for(
        self,
        workspace: &Path,
        shell: ShellAccess,
    ) -> Result<Runtime, RunError> {
        // Path roots are hygiene, not a boundary: per ADR-0004 that is the
        // kernel's job, and per ADR-0013 basis ships no instance of one. What
        // the caller said about commands is passed through as written.
        let policy = git_protected(RuntimePolicy::workspace_bounded(workspace), workspace)
            .allow_shell_commands(shell.is_granted())
            .allow_background_commands(shell.is_granted());

        self.build_with(store::runtime_identifier(workspace), policy)
    }

    fn build_with(self, identifier: String, policy: RuntimePolicy) -> Result<Runtime, RunError> {
        let choice = provider::resolve_with(
            self.provider,
            self.base_url.as_deref(),
            self.api_key.as_deref(),
        )?;

        let dispatch = Arc::new(HookDispatch::new(self.interceptors));

        let builder = mentra::Runtime::builder()
            // Which conversations belong where, which is the only question
            // `session/list` can honestly answer (see `crate::store`). Unset,
            // mentra tags every agent `"default"` and basis's own listing —
            // which filters on this — finds nothing, whatever was persisted.
            .with_runtime_identifier(identifier)
            .with_policy(policy)
            // Without an authorizer mentra allows every call unconditionally,
            // and no permission request can ever be raised — so the gate goes
            // on even for a runtime whose runs approve everything (see
            // `crate::approval`).
            .with_tool_authorizer(ApprovalGate::new())
            // The one tool basis registers (ADR-0016). It has to be on the
            // runtime rather than on a session, because a subagent shares its
            // parent's runtime registry and `spawn` must reach the model at
            // every depth — the uniformity the ADR calls recursive.
            .with_tool(SpawnTool::new())
            // The one pre-hook basis registers, always: mentra takes hooks at
            // build time only, and workspaces arrive later, through the
            // dispatcher (see `runtime::dispatch`).
            .with_pre_hook(DispatchHook(Arc::clone(&dispatch)));

        let builder = if self.command_environment.is_empty() {
            builder
        } else {
            builder.with_executor(EnvironmentExecutor::new(self.command_environment))
        };

        // Left alone unless the caller said something, because mentra's default
        // is a real database a host may already have history in — moving it, or
        // dropping it on the floor, is a thing to be asked for and never a
        // thing to happen by upgrade.
        let builder = match &self.history {
            Some(History::Directory(dir)) => builder.with_store(store::store_in(dir)),
            Some(History::Ephemeral) => builder.with_store(store::volatile()),
            None => builder,
        };

        // `build`, not `build_async`: no MCP server is ever registered at the
        // runtime level, so there is nothing for the async constructor to
        // connect. Workspace-owned connections arrive post-build (ADR-0018).
        let mentra = match &choice.base_url {
            Some(base_url) => {
                builder.with_registered_provider(compatible_provider(base_url, &choice.api_key))
            }
            None => builder.with_provider(choice.provider, choice.api_key.clone()),
        }
        .build()?;

        Ok(Runtime {
            mentra,
            provider: choice.provider,
            provider_label: ProviderId::from(choice.provider).to_string(),
            model: self.model,
            dispatch,
            #[cfg(feature = "mcp")]
            mcp_claims: Mutex::new(HashMap::new()),
        })
    }
}

/// The command posture a shared runtime grants: shell and background on, with
/// `workspace_bounded`'s timeouts, and no path roots of its own.
///
/// Commands are on because ADR-0013 grants them by default and a shared policy
/// cannot say otherwise per workspace — the dispatcher's guard is where a
/// `ShellAccess::Denied` workspace is enforced. No roots, because mentra's
/// file bounding always allows under the calling agent's `base_dir`: with the
/// list empty, each workspace's agents are confined to their own directory and
/// no workspace's root widens another's.
pub(crate) fn shared_policy() -> RuntimePolicy {
    RuntimePolicy::default()
        .allow_shell_commands(true)
        .allow_background_commands(true)
        // workspace_bounded's numbers, restated because that constructor also
        // sets roots this policy must not have. A drift here would give shared
        // and private runtimes different command patience.
        .with_default_command_timeout(std::time::Duration::from_secs(120))
        .with_max_command_timeout(std::time::Duration::from_secs(600))
}

/// Keeps the parts of `.git` that decide what *runs* out of reach.
///
/// `.git/hooks` holds programs git executes on ordinary operations, and
/// `.git/config` can name more of them (`core.hooksPath`, and the `filter`/
/// `diff` drivers that run on checkout). Writing either turns a file edit into
/// code execution outside anything basis's policy or approval covers, which is
/// why they are singled out rather than denying `.git` wholesale — an agent
/// legitimately reads `.git`, and `git` itself must keep writing objects and
/// refs underneath it.
///
/// **This binds the builtin file tools, not the shell.** A command like
/// `sh -c 'echo … > .git/hooks/pre-commit'` still reaches the path, because
/// nothing here parses shell. It closes the route a model actually takes and
/// remains hygiene; per ADR-0004 and ADR-0013 the boundary is the OS's, and
/// basis does not ship one. On shared runtimes the same rule is enforced by the
/// hook dispatcher, which knows which workspace a call belongs to; the private
/// path keeps this policy baking as a second belt.
fn git_protected(policy: RuntimePolicy, workspace: &Path) -> RuntimePolicy {
    let git = workspace.join(".git");
    policy
        .with_denied_write_root(git.join("hooks"))
        .with_denied_write_root(git.join("config"))
}

/// Builds a provider aimed at an OpenAI-compatible endpoint.
///
/// mentra's OpenAI preset is the right shape — the Responses wire format and
/// bearer auth — so basis takes that definition, swaps the base URL, and disables
/// automatic Hybrid HTTP state chaining. Building on the preset avoids
/// describing a provider from scratch and drifting from whatever mentra learns
/// next.
fn compatible_provider(base_url: &str, api_key: &str) -> ResponsesProvider<StaticCredentialSource> {
    let mut definition = responses::openai_definition();
    definition.base_url = Some(base_url.to_string());
    definition.descriptor.display_name = Some(format!("OpenAI-compatible ({base_url})"));

    // A compatible endpoint promises the Responses wire shape, not every
    // optional OpenAI extension. basis already replays the complete local
    // transcript, so do not probe `previous_response_id` support with a
    // request that may fail; native provider presets retain Hybrid chaining.
    ResponsesProvider::new(definition, StaticCredentialSource::new(api_key))
        .without_hybrid_http_previous_response_id()
}

#[cfg(test)]
mod tests;