M0: compilable skeleton — Kigi 0.1.0 fork surgery

Hard fork of xai-org/grok-build (Apache-2.0) re-targeted as Kigi, an
unofficial Kimi Code CLI community build.

Rename & identity
- 72 xai-*/xai-grok-* crates -> kigi-* (explicit: xai-grok-pager-bin ->
  kigi-bin [binary `kigi`], xai-grok-pager -> kigi-tui; rest mechanical);
  ptyctl, ptyctl-cli, third_party/ unchanged; proto package
  xai.grok.tools.v1 -> kigi.tools.v1
- Config home ~/.kigi (KIGI_SHARE_DIR override), env prefix GROK_* ->
  KIGI_*, `kigi --version` carries the unofficial-community-build notice
- clap identity, help text, startup banner, prompt templates rebranded
  (templates re-encrypted)

Deletions (PRD removal list #5/#6/#7/#9/#10)
- voice input (xai-grok-voice) and all TUI wiring
- telemetry: Mixpanel client, external OTel stream, Sentry, OTLP layers,
  trace/GCS/S3 upload queues (kigi-file-utils halved), workspace upload
  module & dc_log, heap-profile uploader, auth-diagnostics uploader,
  session-analytics halves of feedback; local zero-egress observability
  preserved in new kigi-log crate (unified log, --debug firehose,
  subsystem file logs, opt-in instrumentation)
- announcements (crate, remote-settings fields, TUI surfaces)
- plugin marketplace (crate, sources/browse/CTA/extensions-modal tab);
  direct plugin install/uninstall/update via kigi-agent git_install kept
- relay/gateway/assets endpoints and features (agent relay, headless
  relay transport, gateway bridge, LeaderEnvUrls); leader IPC socket now
  ~/.kigi/leader.sock + KIGI_LEADER_SOCKET, no ws-url derivation
- functional types rehomed instead of deleted: PermissionMode ->
  kigi-config-types, McpInitStrategy -> kigi-mcp, PrCreationSource ->
  session signals, TerminalDiagnostics -> kigi-pager-render, agent_id ->
  shell util

Endpoints
- kigi-env rewritten: single production KigiEndpoints {coding_api_base_url
  https://api.kimi.com/coding/v1 (KIGI_CODE_BASE_URL), oauth_host
  https://auth.kimi.com (KIGI_OAUTH_HOST), update_base_url (GitHub
  Releases API), upgrade_page_url}; GrokBuildEnvironment enum deleted

Toolchain & workspace hygiene
- Rust 1.97.0 pinned; edition 2024; full cargo update; git2 hoisted to
  workspace at 0.21 (Option->Result API migration), quick-xml 0.41
- Root Cargo.toml hand-maintained (PRD §8.1): version 0.1.0 inherited by
  all members, members sorted, unused deps pruned
- cargo-deny advisories gate (deny.toml with documented transitive
  exceptions); CI workflow (check/clippy/fmt/deny/test, macOS+Linux)
- cross-crate test seams re-gated behind `test-support` cargo feature;
  insta snapshot baselines renamed to the kigi_tui prefix
- clippy --workspace --all-targets: zero warnings; fmt clean

Fixes surfaced by the port
- updater probe/installer divergence (bin/kigi vs bin/grok symlink set)
- idle model-metadata refresh dead under KIGI_CODE_BASE_URL override
  (new is_effective_coding_endpoint_url, loopback+override aware)
- macOS symlinked-TMPDIR fixture canonicalization (foreign_sessions,
  fast-worktree); RSS measurement tests serialized via serial_test

Docs & legal (Apache §4)
- NOTICE added (upstream attribution + change statement); THIRD-PARTY
  notices sustained; kigi-tools ported-code notices extended; README,
  CONTRIBUTING, SECURITY, AGENTS.md rewritten

Out of scope for M0 (tracked): Kimi auth/inference (M1), search/fetch,
command parity, config import (M2), Computer Hub excision & final
brand-token sweep (M2), distribution & self-update rewrite (M3).

crates/common/kigi-tool-protocol/src/error_wire.rs

@@ -0,0 +1,96 @@
+//! Wire-friendly error type carried inside the JSON-RPC `error.data` field.
+
+use serde::{Deserialize, Serialize};
+
+use crate::{RequestId, ToolId};
+
+/// Stable wire representation of a tool-call failure.
+///
+/// Receivers SHOULD switch on the `code` discriminator (e.g.
+/// `tool_not_found`) rather than the numeric JSON-RPC `error.code`.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, thiserror::Error)]
+#[serde(tag = "code", rename_all = "snake_case")]
+pub enum ToolErrorWire {
+    #[error("tool not found: {tool_id}")]
+    ToolNotFound { tool_id: ToolId },
+
+    #[error("session mismatch")]
+    SessionMismatch,
+
+    #[serde(rename = "forbidden")]
+    #[error("permission denied: {reason}")]
+    PermissionDenied { reason: String },
+
+    #[serde(rename = "connection_lost")]
+    #[error("transport closed for {tool_id}")]
+    TransportClosed { tool_id: ToolId },
+
+    #[error("timeout after {elapsed_ms}ms for {tool_id}")]
+    Timeout { tool_id: ToolId, elapsed_ms: u64 },
+
+    #[error("cancelled")]
+    Cancelled { tool_id: ToolId },
+
+    #[serde(rename = "invalid_params")]
+    #[error("invalid arguments: {message}")]
+    InvalidArguments {
+        message: String,
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        details: Option<serde_json::Value>,
+    },
+
+    #[error("execution error in {tool_id}: {message}")]
+    Execution { tool_id: ToolId, message: String },
+
+    #[error("unsupported protocol version")]
+    UnsupportedProtocolVersion { supported: Vec<String> },
+
+    #[serde(rename = "frame_too_large")]
+    #[error("payload too large: {bytes} bytes (limit {limit})")]
+    PayloadTooLarge { bytes: u64, limit: u64 },
+
+    #[error("behavior_version unsupported")]
+    BehaviorVersionUnsupported { tool_id: ToolId, requested: String },
+
+    /// Render-card budget exceeded for the current session. `card_id`
+    /// carries the offending render-card identifier when known; `reason`
+    /// is a free-form human-readable explanation.
+    #[error("render limited for {tool_id}: {reason}")]
+    RenderLimited {
+        tool_id: ToolId,
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        card_id: Option<String>,
+        reason: String,
+    },
+
+    /// Terminal-tool subprocess sub-call failed. Distinct from
+    /// `Execution` because terminal sub-call failures have a known,
+    /// retry-eligible shape.
+    #[error("terminal subprocess error in {tool_id}: {message}")]
+    TerminalError { tool_id: ToolId, message: String },
+
+    #[serde(rename = "internal_error")]
+    #[error("internal error{}", .detail.as_deref().map(|d| format!(": {d}")).unwrap_or_default())]
+    Internal {
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        request_id: Option<RequestId>,
+        /// Bounded, human-readable cause of the internal error. Optional for
+        /// wire compatibility with older peers; producers SHOULD populate it
+        /// (truncated at the producer) so receivers can distinguish failure
+        /// modes without correlating server logs.
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        detail: Option<String>,
+    },
+
+    /// Free-form forward-compat error. The outer `code` discriminator is
+    /// always the literal `"custom"`; the producer-supplied subcode lives
+    /// in `subcode` (the field can't be named `code` because it would
+    /// collide with the serde discriminator).
+    #[error("custom: {subcode} — {message}")]
+    Custom {
+        subcode: String,
+        message: String,
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        details: Option<serde_json::Value>,
+    },
+}