Module runtime_context 

v0.7.x (issue #1174 follow-up #1192 / #1196) — cross-surface RuntimeContext for substrate state that spans the HTTP daemon, the MCP stdio binary, and the CLI.

Why this module exists

Pre-#1192 / #1196 the substrate carried a handful of process-wide static slots — webhook HMAC override, transcript decompression cap, audit sink + sequence counter, session-recall tracker, X25519 keypair cache — that none of AppState (HTTP), the MCP Connection, or the per-command CLI handlers could own jointly. PR7 (#1192) and PR8 (#1196) on release/v0.7.0 identified that the correct refactor is a single Arc<RuntimeContext> that all three surfaces can hold and that internally backs every former static.

This module is that struct. The design preserves the existing public surface (e.g. crate::config::active_hooks_hmac_secret, crate::audit::emit, crate::reranker::global_session_recall_tracker) — those accessors now delegate to the process-wide RuntimeContext singleton. The wire / chain / cache semantics are byte-for-byte unchanged; the storage merely moved from static FOO: ... = ... to a field on RuntimeContext.

Singleton vs. injected instance

RuntimeContext is a struct, not a global. Tests construct fresh instances via RuntimeContext::default and exercise the typed accessors directly; production code wires a single instance through RuntimeContext::install_global at boot so the legacy free functions (crate::config::set_active_hooks_hmac_secret, crate::audit::emit, etc.) keep working without churning ~60 callsites across the codebase.

The global() accessor returns &'static RuntimeContext (via a LazyLock-style OnceLock seeded on first read). Install order matters only at the very first read; once a context is installed it sticks for the lifetime of the process, matching the prior OnceLock / RwLock<Option<...>> semantics of every individual extracted static.

Structs

AuditState

V-4 audit chain state. Owns the same (sink, sequence) pair the pre-#1192 src/audit.rs module-level statics owned; the public crate::audit::* functions delegate here.

RuntimeContext

Cross-surface substrate state.