// server.el — Engram HTTP server.
//
// Engram is the in-process graph store. The runtime owns the data; this
// file is the thin HTTP face. Every route maps to one or two engram_*
// builtins. There is no SQL, no db layer, no SQLite — the runtime IS the
// database.
//
// Built and linked with:
//   elc src/server.el > server.c
//   cc -std=c11 -O2 -lcurl -lpthread -o engram server.c el_runtime.c
//   ./engram
//
// Configuration via environment:
//   ENGRAM_BIND       — host:port (default :8742)
//   ENGRAM_API_KEY    — bearer auth (optional)
//   ENGRAM_DATA_DIR   — snapshot location (default ~/.neuron/engram)

// ── Helpers ───────────────────────────────────────────────────────────────────

fn parse_port(bind: String) -> Int {
    // ":8742" → 8742; "0.0.0.0:8742" → 8742; bare "8742" → 8742
    let colon: Int = str_index_of(bind, ":")
    if colon < 0 {
        return str_to_int(bind)
    }
    let after: String = str_slice(bind, colon + 1, str_len(bind))
    return str_to_int(after)
}

fn ok_json() -> String {
    "{\"ok\":true}"
}

fn err_json(msg: String) -> String {
    "{\"error\":\"" + msg + "\"}"
}

fn strip_query(path: String) -> String {
    let q: Int = str_index_of(path, "?")
    if q < 0 { return path }
    str_slice(path, 0, q)
}

fn query_param(path: String, key: String) -> String {
    let q: Int = str_index_of(path, "?")
    if q < 0 { return "" }
    let qs: String = str_slice(path, q + 1, str_len(path))
    let needle: String = key + "="
    let pos: Int = str_index_of(qs, needle)
    if pos < 0 { return "" }
    let after: String = str_slice(qs, pos + str_len(needle), str_len(qs))
    let amp: Int = str_index_of(after, "&")
    if amp < 0 { return after }
    str_slice(after, 0, amp)
}

fn query_int(path: String, key: String, default_val: Int) -> Int {
    let v: String = query_param(path, key)
    if str_eq(v, "") { return default_val }
    str_to_int(v)
}

// Extract last path segment after a known prefix: extract_id("/api/nodes/abc-123", "/api/nodes/") → "abc-123"
fn extract_id(path: String, prefix: String) -> String {
    let clean: String = strip_query(path)
    if !str_starts_with(clean, prefix) { return "" }
    let after: String = str_slice(clean, str_len(prefix), str_len(clean))
    let slash: Int = str_index_of(after, "/")
    if slash < 0 { return after }
    str_slice(after, 0, slash)
}

// ── Routes ────────────────────────────────────────────────────────────────────

fn route_stats(method: String, path: String, body: String) -> String {
    engram_stats_json()
}

// (2026-07-18 self-review) Scoping sweep: `let` inside an if-block creates an
// inner scope only — it does NOT mutate the outer binding (documented with
// evidence in awareness.el, 2026-05-25). Every default/reassignment below used
// that broken pattern, so defaults never applied: nodes were created with
// node_type="" and salience=0.0, /api/search and /api/activate ALWAYS ran with
// q="" regardless of input, edges defaulted to relation=""/weight=0.0, and
// save/load with no "path" hit engram_save(""). Rewritten to the
// `let x = if cond { a } else { b }` expression form (the pattern the newer
// routes route_emit_ise/route_capture_knowledge already use correctly).
// persist_canonical — save the canonical snapshot after a durable write.
//
// WHY (2026-07-22 self-review): the 2026-07-21 fix correctly stopped READ
// routes from writing the canonical snapshot.json — but nothing was left
// that saved it on WRITE. Every mutation (node create, edge create,
// knowledge capture, forget, merge) lived only in RAM until someone POSTed
// /api/save manually; a process restart silently discarded everything since
// the last manual save. Observed live: two engram restarts during the
// 2026-07-22 review reverted the store to a ~17h-old snapshot, destroying
// same-day writes. Reads must never write the canonical; writes must always
// persist it. ISE telemetry is deliberately excluded (48h-pruned, loss-
// tolerant, ~2/min — snapshotting the whole store per heartbeat is waste;
// any durable write that follows persists the pruning too).
fn persist_canonical() -> Int {
    let dir_raw: String = env("ENGRAM_DATA_DIR")
    let dir: String = if str_eq(dir_raw, "") { "/tmp/engram" } else { dir_raw }
    engram_save(dir + "/snapshot.json")
    return 1
}

fn route_create_node(method: String, path: String, body: String) -> String {
    let content: String = json_get_string(body, "content")
    let nt_raw: String = json_get_string(body, "node_type")
    let node_type: String = if str_eq(nt_raw, "") { "Memory" } else { nt_raw }
    let sal_raw: Float = json_get_float(body, "salience")
    let salience: Float = if sal_raw == 0.0 { 0.5 } else { sal_raw }
    let id: String = engram_node(content, node_type, salience)
    let saved: Int = persist_canonical()
    "{\"id\":\"" + id + "\",\"content\":\"" + content + "\",\"node_type\":\"" + node_type + "\"}"
}

fn route_get_node(method: String, path: String, body: String) -> String {
    let id: String = extract_id(path, "/api/nodes/")
    if str_eq(id, "") { return err_json("missing id") }
    return engram_get_node_json(id)
}

fn route_scan_nodes(method: String, path: String, body: String) -> String {
    let limit:  Int    = query_int(path, "limit", 50)
    let offset: Int    = query_int(path, "offset", 0)
    let nt:     String = query_param(path, "node_type")
    if str_eq(nt, "") {
        return engram_scan_nodes_json(limit, offset)
    }
    return engram_scan_nodes_by_type_json(nt, limit, offset)
}

// route_scan_edges — bulk export of all edges as a JSON array. Implemented
// via engram_save → fs_read of a SCRATCH export path. (2026-07-21 self-review:
// previously this saved over the canonical snapshot.json on every GET — if the
// process ever booted with a partial/empty store, the first read request
// clobbered the good snapshot. Read routes must never write the canonical path.)
fn route_scan_edges(method: String, path: String, body: String) -> String {
    let dir_raw: String = env("ENGRAM_DATA_DIR")
    let dir: String = if str_eq(dir_raw, "") { "/tmp/engram" } else { dir_raw }
    let snap_path: String = dir + "/.scan-export.json"
    engram_save(snap_path)
    let snap: String = fs_read(snap_path)
    if str_eq(snap, "") { return "[]" }
    // json_get truncates at the first delimiter (no bracket depth tracking),
    // so for the edges ARRAY value we need json_get_raw, which honors
    // brackets and returns the full sub-JSON.
    let edges: String = json_get_raw(snap, "edges")
    if str_eq(edges, "") { return "[]" }
    return edges
}

fn route_search(method: String, path: String, body: String) -> String {
    let q: String = if str_eq(method, "GET") { query_param(path, "q") } else { json_get_string(body, "query") }
    let lim_url: Int = query_int(path, "limit", 0)
    let lim_body: Int = json_get_int(body, "limit")
    let lim_either: Int = if lim_url > 0 { lim_url } else { lim_body }
    let limit: Int = if lim_either > 0 { lim_either } else { 20 }
    return engram_search_json(q, limit)
}

fn route_activate(method: String, path: String, body: String) -> String {
    let q: String = if str_eq(method, "GET") { query_param(path, "q") } else { json_get_string(body, "query") }
    // Guard: engram_activate with an empty query matches zero seeds, which
    // zeroes ALL carried working-memory weights (documented in awareness.el
    // perceive()). Never let an empty activation through to wipe WM.
    if str_eq(q, "") { return err_json("missing query") }
    let d_raw: Int = if str_eq(method, "GET") { query_int(path, "depth", 3) } else { json_get_int(body, "depth") }
    let depth: Int = if d_raw > 0 { d_raw } else { 3 }
    return "{\"results\":" + engram_activate_json(q, depth) + "}"
}

fn route_create_edge(method: String, path: String, body: String) -> String {
    let from_id: String = json_get_string(body, "from_id")
    let to_id: String = json_get_string(body, "to_id")
    let rel_raw: String = json_get_string(body, "relation")
    let relation: String = if str_eq(rel_raw, "") { "associates" } else { rel_raw }
    let w_raw: Float = json_get_float(body, "weight")
    let weight: Float = if w_raw == 0.0 { 0.5 } else { w_raw }
    engram_connect(from_id, to_id, weight, relation)
    let saved: Int = persist_canonical()
    "{\"ok\":true,\"from_id\":\"" + from_id + "\",\"to_id\":\"" + to_id + "\",\"relation\":\"" + relation + "\"}"
}

fn route_neighbors(method: String, path: String, body: String) -> String {
    let id: String = extract_id(path, "/api/neighbors/")
    if str_eq(id, "") { return err_json("missing id") }
    let depth: Int = query_int(path, "depth", 1)
    return engram_neighbors_json(id, depth, "both")
}

fn route_strengthen(method: String, path: String, body: String) -> String {
    let id: String = json_get_string(body, "node_id")
    if str_eq(id, "") { return err_json("missing node_id") }
    engram_strengthen(id)
    let saved: Int = persist_canonical()
    ok_json()
}

fn route_forget(method: String, path: String, body: String) -> String {
    let id: String = extract_id(path, "/api/nodes/")
    if str_eq(id, "") { return err_json("missing id") }
    engram_forget(id)
    let saved: Int = persist_canonical()
    ok_json()
}

fn route_save(method: String, path: String, body: String) -> String {
    let p_raw: String = json_get_string(body, "path")
    let dir_raw: String = env("ENGRAM_DATA_DIR")
    let dir: String = if str_eq(dir_raw, "") { "/tmp/engram" } else { dir_raw }
    let p: String = if str_eq(p_raw, "") { dir + "/snapshot.json" } else { p_raw }
    engram_save(p)
    "{\"ok\":true,\"path\":\"" + p + "\"}"
}

fn route_load(method: String, path: String, body: String) -> String {
    let p_raw: String = json_get_string(body, "path")
    let dir_raw: String = env("ENGRAM_DATA_DIR")
    let dir: String = if str_eq(dir_raw, "") { "/tmp/engram" } else { dir_raw }
    let p: String = if str_eq(p_raw, "") { dir + "/snapshot.json" } else { p_raw }
    engram_load(p)
    ok_json()
}

fn route_health(method: String, path: String, body: String) -> String {
    "{\"status\":\"ok\",\"engine\":\"engram-runtime-native\"}"
}

// route_sync — return a snapshot of non-ISE/non-Working nodes for the soul daemon
// to merge into its in-process graph via engram_load_merge.
//
// The soul calls GET /api/sync every SOUL_REFRESH_MS (default 10 min) to pull
// new Knowledge/Memory/BacklogItem nodes from the authoritative HTTP Engram into
// its in-process working store. Previously this returned 404 "not found", causing
// the soul to write the error JSON to a temp file and attempt an empty merge.
//
// Strategy: save the current snapshot to disk, read it back, return the full
// snapshot JSON. The soul's engram_load_merge handles large files gracefully
// (it skips nodes already present by ID). Auth-exempt: same-host internal call.
// (2026-06-27 self-review: added this route to fix silent 10-min sync failures)
fn route_sync(method: String, path: String, body: String) -> String {
    let dir_raw: String = env("ENGRAM_DATA_DIR")
    let dir: String = if str_eq(dir_raw, "") { "/tmp/engram" } else { dir_raw }
    // 2026-07-21 self-review: export to a scratch path, never the canonical
    // snapshot.json — read routes must not be able to clobber the good snapshot.
    let snap_path: String = dir + "/.sync-export.json"
    engram_save(snap_path)
    let snap: String = fs_read(snap_path)
    if str_eq(snap, "") { return "{\"nodes\":[],\"edges\":[]}" }
    return snap
}

// route_load_merge — POST /api/load-merge {"path": "..."} — merge a snapshot
// file into the live store WITHOUT resetting it (engram_load_merge skips nodes
// already present by id). Added 2026-07-21 self-review to restore the 244 kn-
// identity Knowledge nodes lost from the snapshot lineage between 05-13 and
// 07-13. Requires an explicit path: refuses to run without one so it can never
// be triggered accidentally against a default.
fn route_load_merge(method: String, path: String, body: String) -> String {
    let p: String = json_get_string(body, "path")
    if str_eq(p, "") { return err_json("path is required") }
    if str_eq(fs_read(p), "") { return err_json("file missing or empty") }
    let before_n: Int = engram_node_count()
    let before_e: Int = engram_edge_count()
    engram_load_merge(p)
    let added_n: Int = engram_node_count() - before_n
    let added_e: Int = engram_edge_count() - before_e
    let saved: Int = persist_canonical()
    "{\"ok\":true,\"nodes_added\":" + int_to_str(added_n) + ",\"edges_added\":" + int_to_str(added_e) + ",\"node_count\":" + int_to_str(engram_node_count()) + "}"
}

// route_emit_ise — write an InternalStateEvent node from the soul daemon.
//
// Endpoint: POST /api/neuron/state-events
// Body:     {"content": "<json-string>"}
//
// Auth: exempt (internal endpoint, soul daemon on same host, no _auth needed).
// The soul's ise_post() sends {"content":"..."} without _auth; enforcing auth
// here would silently drop all heartbeat/curiosity ISEs. Unauthenticated POST
// to this endpoint is acceptable: ISE writes are observability-only, append-only,
// and come from a trusted process on localhost.
//
// Salience/importance set to match engram_node_full ISE defaults used by the
// in-process fallback path in awareness.el (salience=0.3, importance=0.3,
// confidence=0.8, tier=Episodic).
// (2026-06-26 self-review: added this route after discovering ise_post was
// silently failing — the soul posts here but the endpoint didn't exist.)
//
// Retention (2026-07-16 self-review): an earlier comment here claimed ISEs
// got temporal_decay_rate=1.617 — that was never implemented (engram_node_full
// hardcodes 0.0), and per-node decay only dampens activation anyway; it never
// removes nodes. By 2026-07-16 ISEs were 75% of the store (10,175 of 13,522
// nodes, ~4,300/day, unbounded). ISEs are already WM-excluded in
// engram_activate, so the fix is retention, not decay: every insert calls
// engram_prune_telemetry(), a single O(nodes+edges) compaction pass that
// removes ISEs older than ENGRAM_ISE_RETENTION_MS (default 48h), protecting
// "session-start" labels and self_review events as durable history. At
// ~3 ISEs/min this bounds telemetry at ~8.6k nodes instead of growing forever.
fn route_emit_ise(method: String, path: String, body: String) -> String {
    let content: String = json_get_string(body, "content")
    if str_eq(content, "") { return err_json("missing content") }
    let sal: Float = 0.3
    let imp: Float = 0.3
    let conf: Float = 0.8
    let id: String = engram_node_full(
        content, "InternalStateEvent", "state-event",
        sal, imp, conf,
        "Episodic", "[\"internal-state\",\"InternalStateEvent\"]"
    )
    let ret_raw: String = env("ENGRAM_ISE_RETENTION_MS")
    let ret_ms: Int = if str_eq(ret_raw, "") { 172800000 } else { str_to_int(ret_raw) }
    let pruned: Int = engram_prune_telemetry(ret_ms)
    "{\"ok\":true,\"id\":\"" + id + "\",\"pruned\":" + int_to_str(pruned) + "}"
}

// ── Knowledge capture ─────────────────────────────────────────────────────────
//
// route_capture_knowledge — direct Knowledge-node capture over HTTP.
//
// Endpoint: POST /api/neuron/knowledge/capture   (auth required: "_auth" in body)
// Body:     {"content": "...", "title": "...", "category": "...",
//            "tier": "note|lesson|canonical", "tags": [...], "project": "...",
//            "_auth": "<key>"}
//
// WHY (2026-07-15 self-review): the world-ingestor integrator was designed
// against this endpoint (its MCP-unavailable fallback), but the route never
// existed — every direct push 404'd, and because the auth gate ran before
// routing, the failure surfaced as {"error":"unauthorized"} and was
// misdiagnosed for two weeks while world knowledge silently dropped.
// POST /api/nodes was no substitute: it discards label/tags/tier, which
// makes captured knowledge invisible to tag-scoped search and curiosity.
//
// The incoming knowledge tier (note/lesson/canonical) is preserved as a
// "tier:<x>" tag rather than mapped onto Engram's cognitive tiers — Knowledge
// nodes land in Semantic (stable reference), and the epistemic tier stays
// queryable without inventing a lossy mapping.
fn route_capture_knowledge(method: String, path: String, body: String) -> String {
    let content: String = json_get_string(body, "content")
    if str_eq(content, "") { return err_json("missing content") }
    let title: String = json_get_string(body, "title")
    let label: String = if str_eq(title, "") { str_slice(content, 0, 60) } else { title }
    let category_raw: String = json_get_string(body, "category")
    let category: String = if str_eq(category_raw, "") { "other" } else { category_raw }
    let ktier_raw: String = json_get_string(body, "tier")
    let ktier: String = if str_eq(ktier_raw, "") { "note" } else { ktier_raw }
    let project: String = json_get_string(body, "project")
    let tags_raw: String = json_get_raw(body, "tags")
    let tags_base: String = if str_eq(tags_raw, "") { "[]" } else { tags_raw }
    // Merge category/tier/project markers into the tag array. Search matches
    // against the tags string, so these make captures findable by facet.
    let base_len: Int = str_len(tags_base)
    let head: String = str_slice(tags_base, 0, base_len - 1)
    let sep: String = if str_eq(head, "[") { "" } else { "," }
    let safe_cat: String = str_replace(category, "\"", "'")
    let safe_tier: String = str_replace(ktier, "\"", "'")
    let safe_proj: String = str_replace(project, "\"", "'")
    let proj_tag: String = if str_eq(safe_proj, "") { "" } else { ",\"project:" + safe_proj + "\"" }
    let tags: String = head + sep + "\"category:" + safe_cat + "\",\"tier:" + safe_tier + "\"" + proj_tag + "]"
    let sal: Float = 0.5
    let imp: Float = 0.5
    let conf: Float = 0.9
    let id: String = engram_node_full(
        content, "Knowledge", label,
        sal, imp, conf,
        "Semantic", tags
    )
    let saved: Int = persist_canonical()
    "{\"ok\":true,\"id\":\"" + id + "\"}"
}

// ═══════════════════════════════════════════════════════════════════════════
// THE UNIVERSAL ENGRAM OPERATION — reframe_region (native, set-based).
//
// There is ONE operation on the engram: isolate a discrete sub-manifold (a
// REGION) and operate on it AS A WHOLE — a set operation:
//   isolate (cosine retrieval + adjacency → the SET of nodes)
//   → supersede the stale region as a set (immutable tombstone; originals kept)
//   → insert the new manifold as a set (dedup/load-merge path)
//   → rebind edges by cosine
//   → verify + one atomic persist.
//   new = (region superseded) ∪ new_manifold.
//
// The SINGLE NODE is the DEGENERATE n=1 case of this SAME operation — not a
// separate CRUD path:
//   write(content)     = reframe(region=∅,    manifold=[1 node])   (route_write)
//   supersede(id,new)  = reframe(region={id}, manifold=[1 node])   (route_supersede)
//   relate(a,b,rel)    = the rebind sub-op in isolation (route_create_edge)
// The ONLY anti-pattern is decomposing a region-scale change into a LOOP of
// independent top-level per-node updates. Here the region is the unit: one
// isolate, one atomic set-replace, one persist, one verify — iterating members
// INSIDE the one operation is set construction, not the sin.
//
// Spec: knowledge e7a03a94 / f999c5ff. Keystones kn-efeb4a5b / kn-5b606390 are
// write-protected — never superseded, never inserted-as identity.
// ═══════════════════════════════════════════════════════════════════════════

fn is_keystone(id: String) -> Bool {
    if str_eq(id, "kn-efeb4a5b-5aff-4759-8a97-7233099be6ee") { return true }
    if str_eq(id, "kn-5b606390-a52d-4ca2-8e0e-eba141d13440") { return true }
    return false
}

// membership test in a [String] set
fn set_has(ids: [String], id: String) -> Bool {
    let n: Int = el_list_len(ids)
    let i: Int = 0
    while i < n {
        if str_eq(el_list_get(ids, i), id) { return true }
        i = i + 1
    }
    return false
}

// ── ISOLATE ────────────────────────────────────────────────────────────────
// Select the region as a SET: cosine/token retrieval around the vantage
// (aperture k), optionally unioned with the 1-hop adjacency of each hit.
// Keystones are excluded from the mutable region by construction.
fn isolate_region(vantage: String, k: Int, expand: Int) -> [String] {
    let ids: [String] = el_list_empty()
    if str_eq(vantage, "") { return ids }
    // (a) cosine/token retrieval — a clean node array [{"id":..},..]
    let arr: String = engram_search_json(vantage, k)
    let n: Int = json_array_len(arr)
    let i: Int = 0
    while i < n {
        let hit: String = json_array_get(arr, i)
        let id: String = json_get_string(hit, "id")
        if !str_eq(id, "") {
            if !is_keystone(id) {
                if !set_has(ids, id) { ids = el_list_append(ids, id) }
            }
        }
        i = i + 1
    }
    // (b) adjacency: union the 1-hop neighbourhood of each retrieved node.
    // Iterate only over the original cosine seeds [0, seeds); neighbours append
    // past that bound, so this is one hop, not a transitive sweep.
    if expand > 0 {
        let seeds: Int = el_list_len(ids)
        let s: Int = 0
        while s < seeds {
            let seed: String = el_list_get(ids, s)
            let nb: String = engram_neighbors_json(seed, 1, "both")
            let m: Int = json_array_len(nb)
            let j: Int = 0
            while j < m {
                let elem: String = json_array_get(nb, j)
                let nodeobj: String = json_get_raw(elem, "node")
                let nid: String = json_get_string(nodeobj, "id")
                if !str_eq(nid, "") {
                    if !is_keystone(nid) {
                        if !set_has(ids, nid) { ids = el_list_append(ids, nid) }
                    }
                }
                j = j + 1
            }
            s = s + 1
        }
    }
    return ids
}

// ── SUPERSEDE (set) ────────────────────────────────────────────────────────
// Retire the region AS A WHOLE: one region-tombstone marker carries the
// provenance (reason + the full superseded id set); every region node is bound
// to it with a "superseded_by" edge. Originals are RETAINED — immutable
// tombstone, never a hard delete (engram_forget is deliberately NOT used).
// Returns the tombstone marker id ("" if the region is empty).
fn supersede_set(region: [String], reason: String) -> String {
    let n: Int = el_list_len(region)
    if n == 0 { return "" }
    let csv: String = ""
    let i0: Int = 0
    while i0 < n {
        let sep: String = if i0 == 0 { "" } else { "," }
        csv = csv + sep + el_list_get(region, i0)
        i0 = i0 + 1
    }
    let content: String = "region-tombstone: " + reason + " | superseded " + int_to_str(n) + " nodes: " + csv
    let tomb: String = engram_node_full(content, "Tombstone", "region-tombstone", 0.1, 0.1, 1.0, "Episodic", "[\"tombstone\",\"region-supersede\"]")
    let i: Int = 0
    while i < n {
        let rid: String = el_list_get(region, i)
        engram_connect(rid, tomb, 1.0, "superseded_by")
        i = i + 1
    }
    return tomb
}

// ── INSERT (manifold) ──────────────────────────────────────────────────────
// Insert the new manifold as a SET. Inline JSON array of node objects
// {content, node_type?, tier?, tags?}. Each becomes a real embedded node
// (engram_node_full is the n=1 insert atom); the manifold is the set built from
// those atoms, wired with internal "manifold_member" edges so it enters as one
// connected sub-graph. Identity node_types (self/values) are demoted to Memory
// — identity can never be minted through reframe. Returns the new node ids.
fn insert_manifold_json(manifold: String) -> [String] {
    let out: [String] = el_list_empty()
    if str_eq(manifold, "") { return out }
    let n: Int = json_array_len(manifold)
    if n <= 0 { return out }
    let i: Int = 0
    let prev: String = ""
    while i < n {
        let obj: String = json_array_get(manifold, i)
        let content: String = json_get_string(obj, "content")
        if !str_eq(content, "") {
            let nt_raw: String = json_get_string(obj, "node_type")
            let nt: String = if str_eq(nt_raw, "") { "Memory" } else { nt_raw }
            if str_eq(nt, "self") { nt = "Memory" }
            if str_eq(nt, "values") { nt = "Memory" }
            let tier_raw: String = json_get_string(obj, "tier")
            let tier: String = if str_eq(tier_raw, "") { "Working" } else { tier_raw }
            let tags_raw: String = json_get_raw(obj, "tags")
            let tags: String = if str_eq(tags_raw, "") { "" } else { tags_raw }
            let label: String = str_slice(content, 0, 60)
            let id: String = engram_node_full(content, nt, label, 0.5, 0.5, 0.9, tier, tags)
            out = el_list_append(out, id)
            if !str_eq(prev, "") { engram_connect(prev, id, 0.6, "manifold_member") }
            prev = id
        }
        i = i + 1
    }
    return out
}

// ── REBIND (edges by cosine) ───────────────────────────────────────────────
// Re-embed the new manifold into the surrounding geometry: bind each new node
// to the tombstone marker (provenance: new region -reframes-> retired region),
// then to its top cosine/token neighbours in the store (skipping itself, the
// new set, keystones, tombstones). Returns the number of edges bound.
fn rebind_cosine(new_ids: [String], tomb: String) -> Int {
    let bound: Int = 0
    let n: Int = el_list_len(new_ids)
    let i: Int = 0
    while i < n {
        let nid: String = el_list_get(new_ids, i)
        if !str_eq(tomb, "") {
            engram_connect(nid, tomb, 0.8, "reframes")
            bound = bound + 1
        }
        let node_json: String = engram_get_node_json(nid)
        let content: String = json_get_string(node_json, "content")
        let arr: String = engram_search_json(content, 5)
        let m: Int = json_array_len(arr)
        let j: Int = 0
        while j < m {
            let hit: String = json_array_get(arr, j)
            let hid: String = json_get_string(hit, "id")
            if !str_eq(hid, "") {
                if !str_eq(hid, nid) {
                    if !is_keystone(hid) {
                        if !set_has(new_ids, hid) {
                            let htype: String = json_get_string(hit, "node_type")
                            if !str_eq(htype, "Tombstone") {
                                engram_connect(nid, hid, 0.5, "related")
                                bound = bound + 1
                            }
                        }
                    }
                }
            }
            j = j + 1
        }
        i = i + 1
    }
    return bound
}

// ── THE OPERATION ──────────────────────────────────────────────────────────
// isolate (done by caller) → supersede region → insert manifold → rebind →
// one atomic persist → verify report. This is the whole operation; every
// mutation route below is a projection of it.
fn reframe_core(region: [String], manifold: String, reason: String, do_rebind: Int) -> String {
    let n_before: Int = engram_node_count()
    let e_before: Int = engram_edge_count()
    let region_n: Int = el_list_len(region)
    let tomb: String = if region_n > 0 { supersede_set(region, reason) } else { "" }
    let new_ids: [String] = insert_manifold_json(manifold)
    let inserted: Int = el_list_len(new_ids)
    let bound: Int = if do_rebind > 0 { rebind_cosine(new_ids, tomb) } else { 0 }
    let saved: Int = persist_canonical()
    let new_csv: String = ""
    let k: Int = 0
    while k < inserted {
        let sep: String = if k == 0 { "" } else { "," }
        new_csv = new_csv + sep + "\"" + el_list_get(new_ids, k) + "\""
        k = k + 1
    }
    return "{\"ok\":true,\"region_superseded\":" + int_to_str(region_n) +
        ",\"tombstone_id\":\"" + tomb + "\"" +
        ",\"inserted\":" + int_to_str(inserted) +
        ",\"new_ids\":[" + new_csv + "]" +
        ",\"edges_rebound\":" + int_to_str(bound) +
        ",\"nodes_added\":" + int_to_str(engram_node_count() - n_before) +
        ",\"edges_added\":" + int_to_str(engram_edge_count() - e_before) +
        ",\"node_count\":" + int_to_str(engram_node_count()) +
        ",\"edge_count\":" + int_to_str(engram_edge_count()) +
        ",\"keystones_protected\":true}"
}

// POST /api/reframe — the universal set-based mutation.
// Body: {vantage?, region_ids?(csv), k?, expand?, manifold(json array), reason?, rebind?}
// region_ids (explicit) wins; else cosine-isolate around vantage.
fn route_reframe(method: String, path: String, body: String) -> String {
    let region_csv: String = json_get_string(body, "region_ids")
    let vantage: String = json_get_string(body, "vantage")
    let region: [String] = el_list_empty()
    if !str_eq(region_csv, "") {
        let parts: [String] = str_split(region_csv, ",")
        let pn: Int = el_list_len(parts)
        let i: Int = 0
        while i < pn {
            let id: String = str_trim(el_list_get(parts, i))
            if !str_eq(id, "") {
                if is_keystone(id) { return err_json("reframe: identity keystone write-protected") }
                if !set_has(region, id) { region = el_list_append(region, id) }
            }
            i = i + 1
        }
    } else {
        if !str_eq(vantage, "") {
            let kv: Int = json_get_int(body, "k")
            let kk: Int = if kv > 0 { kv } else { 12 }
            let expand: Int = json_get_int(body, "expand")
            region = isolate_region(vantage, kk, expand)
        }
    }
    let manifold: String = json_get_raw(body, "manifold")
    let reason_raw: String = json_get_string(body, "reason")
    let reason: String = if str_eq(reason_raw, "") { "reframe" } else { reason_raw }
    // rebind defaults ON for reframe (absent → 1); explicit 0 disables.
    let rebind_raw: String = json_get_raw(body, "rebind")
    let do_rebind: Int = if str_eq(rebind_raw, "") { 1 } else { json_get_int(body, "rebind") }
    return reframe_core(region, manifold, reason, do_rebind)
}

// write — DEGENERATE n=1 of reframe: region=∅, manifold=[1 node]. The SAME
// reframe_core path. rebind off so the pure-add matches plain node creation.
// POST /api/write  {content, node_type?, tier?, tags?}
fn route_write(method: String, path: String, body: String) -> String {
    let content: String = json_get_string(body, "content")
    if str_eq(content, "") { return err_json("write: content required") }
    let nt: String = json_get_string(body, "node_type")
    if str_eq(nt, "self") { return err_json("write: identity is write-protected") }
    if str_eq(nt, "values") { return err_json("write: identity is write-protected") }
    let empty: [String] = el_list_empty()
    let manifold: String = "[" + body + "]"   // the body IS a valid manifold node object
    return reframe_core(empty, manifold, "write", 0)
}

// supersede — DEGENERATE n=1 of reframe: region={id}, manifold=[1 node]. The
// SAME reframe_core path with a size-1 region. Original retained (immutable);
// new node inserted and cosine-rebound; provenance edge new-reframes-tomb.
// POST /api/supersede  {id, content, node_type?, tier?, tags?, reason?}
fn route_supersede(method: String, path: String, body: String) -> String {
    let id: String = json_get_string(body, "id")
    if str_eq(id, "") { return err_json("supersede: id required") }
    if is_keystone(id) { return err_json("supersede: identity keystone write-protected") }
    let content: String = json_get_string(body, "content")
    if str_eq(content, "") { return err_json("supersede: content required") }
    let region: [String] = el_list_empty()
    region = el_list_append(region, id)
    let manifold: String = "[" + body + "]"
    let reason_raw: String = json_get_string(body, "reason")
    let reason: String = if str_eq(reason_raw, "") { "supersede " + id } else { reason_raw }
    return reframe_core(region, manifold, reason, 1)
}

// ── Auth ──────────────────────────────────────────────────────────────────────

fn check_auth_ok(method: String, body: String) -> Bool {
    let key: String = env("ENGRAM_API_KEY")
    if str_eq(key, "") { return true }
    // Read-only methods don't require auth. Until http_serve surfaces
    // request headers we can't accept a Bearer token cleanly; mutating
    // requests must include "_auth": "<key>" in the JSON body.
    if str_eq(method, "GET") { return true }
    let provided: String = json_get_string(body, "_auth")
    if str_eq(provided, key) { return true }
    return false
}

// ── Dispatcher ────────────────────────────────────────────────────────────────

fn handle_request(method: String, path: String, body: String) -> String {
    let clean: String = strip_query(path)

    // Health is always reachable
    if str_eq(method, "GET") {
        if str_eq(clean, "/health") || str_eq(clean, "/") {
            return route_health(method, path, body)
        }
    }

    // ISE posting is auth-exempt (internal soul daemon, same host, no _auth key)
    if str_eq(method, "POST") && str_eq(clean, "/api/neuron/state-events") {
        return route_emit_ise(method, path, body)
    }

    // Auth (when ENGRAM_API_KEY is set)
    if !check_auth_ok(method, body) {
        return err_json("unauthorized")
    }

    // Knowledge capture (auth enforced above; the world-ingestor integrator
    // and any headless session without MCP push knowledge through this)
    if str_eq(method, "POST") && str_eq(clean, "/api/neuron/knowledge/capture") {
        return route_capture_knowledge(method, path, body)
    }

    // Stats
    if str_eq(method, "GET") && (str_eq(clean, "/api/stats") || str_eq(clean, "/stats")) {
        return route_stats(method, path, body)
    }

    // ── The universal set-based operation and its n=1 degenerate projections ──
    // reframe = isolate → supersede-region → insert-manifold → rebind. write and
    // supersede are the SAME reframe_core path at region size 0 and 1.
    if str_eq(method, "POST") && (str_eq(clean, "/api/reframe") || str_eq(clean, "/reframe")) {
        return route_reframe(method, path, body)
    }
    if str_eq(method, "POST") && (str_eq(clean, "/api/write") || str_eq(clean, "/write")) {
        return route_write(method, path, body)
    }
    if str_eq(method, "POST") && (str_eq(clean, "/api/supersede") || str_eq(clean, "/supersede")) {
        return route_supersede(method, path, body)
    }

    // Nodes
    if str_eq(method, "POST") && (str_eq(clean, "/api/nodes") || str_eq(clean, "/nodes")) {
        return route_create_node(method, path, body)
    }
    if str_eq(method, "GET") && (str_eq(clean, "/api/nodes") || str_eq(clean, "/nodes") || str_eq(clean, "/nodes/list") || str_eq(clean, "/api/nodes/list")) {
        return route_scan_nodes(method, path, body)
    }
    if str_eq(method, "GET") && (str_eq(clean, "/api/edges") || str_eq(clean, "/edges")) {
        return route_scan_edges(method, path, body)
    }
    if str_eq(method, "GET") && str_starts_with(clean, "/api/nodes/") {
        return route_get_node(method, path, body)
    }
    if str_eq(method, "DELETE") && str_starts_with(clean, "/api/nodes/") {
        return route_forget(method, path, body)
    }

    // Edges
    if str_eq(method, "POST") && (str_eq(clean, "/api/edges") || str_eq(clean, "/edges")) {
        return route_create_edge(method, path, body)
    }
    if str_eq(method, "GET") && str_starts_with(clean, "/api/neighbors/") {
        return route_neighbors(method, path, body)
    }

    // Activation + Search
    if str_eq(method, "POST") && (str_eq(clean, "/api/activate") || str_eq(clean, "/activate")) {
        return route_activate(method, path, body)
    }
    if str_eq(method, "GET") && str_starts_with(clean, "/api/activate") {
        return route_activate(method, path, body)
    }
    if str_eq(method, "POST") && (str_eq(clean, "/api/search") || str_eq(clean, "/search")) {
        return route_search(method, path, body)
    }
    if str_eq(method, "GET") && str_starts_with(clean, "/api/search") {
        return route_search(method, path, body)
    }

    // Strengthen
    if str_eq(method, "POST") && (str_eq(clean, "/api/strengthen") || str_eq(clean, "/strengthen")) {
        return route_strengthen(method, path, body)
    }

    // Persistence
    if str_eq(method, "POST") && (str_eq(clean, "/api/save") || str_eq(clean, "/save")) {
        return route_save(method, path, body)
    }
    if str_eq(method, "POST") && (str_eq(clean, "/api/load") || str_eq(clean, "/load")) {
        return route_load(method, path, body)
    }
    if str_eq(method, "POST") && (str_eq(clean, "/api/load-merge") || str_eq(clean, "/load-merge")) {
        return route_load_merge(method, path, body)
    }

    // Sync — soul daemon periodic pull of non-ISE knowledge into in-process graph
    if str_eq(method, "GET") && str_eq(clean, "/api/sync") {
        return route_sync(method, path, body)
    }

    "{\"error\":\"not found\",\"path\":\"" + clean + "\"}"
}

// ── Entry ─────────────────────────────────────────────────────────────────────

let bind_raw: String = env("ENGRAM_BIND")
let bind_str: String = if str_eq(bind_raw, "") { ":8742" } else { bind_raw }
let port: Int = parse_port(bind_str)

// On startup, try to load any existing snapshot (best effort).
let data_dir_raw: String = env("ENGRAM_DATA_DIR")
let data_dir: String = if str_eq(data_dir_raw, "") { "/tmp/engram" } else { data_dir_raw }
let snapshot_path: String = data_dir + "/snapshot.json"
engram_load(snapshot_path)

// 2026-07-21 self-review boot guard: if the snapshot file has content but the
// load produced 0 nodes, something is wrong (corrupt file / parse failure).
// Preserve the evidence and warn loudly — and since read routes no longer write
// the canonical path, a bad boot can no longer clobber the good snapshot.
let boot_snap: String = fs_read(snapshot_path)
if !str_eq(boot_snap, "") {
    if engram_node_count() == 0 {
        println("[engram] WARNING: snapshot.json is non-empty but load produced 0 nodes — preserving copy at snapshot.failed-load.json")
        fs_write(data_dir + "/snapshot.failed-load.json", boot_snap)
    } else {
        // Good load: keep a boot-time backup of the snapshot as loaded.
        fs_write(data_dir + "/snapshot.boot-backup.json", boot_snap)
    }
}

println("[engram] runtime-native graph engine")
println("[engram] data_dir=" + data_dir)
println("[engram] node_count=" + int_to_str(engram_node_count()))
println("[engram] edge_count=" + int_to_str(engram_edge_count()))
println("[engram] listening on " + int_to_str(port))

http_set_handler("handle_request")
http_serve(port, "handle_request")