diff --git a/jolt-core/clojure/core/30-macros.clj b/jolt-core/clojure/core/30-macros.clj
index 34eaa4b..79001fd 100644
--- a/jolt-core/clojure/core/30-macros.clj
+++ b/jolt-core/clojure/core/30-macros.clj
@@ -12,6 +12,11 @@
 
 (defmacro comment [& body] nil)
 
+;; with-out-str: capture everything the body prints to *out* and return it as a
+;; string. __with-out-str (clojure.core) runs the thunk with the output captured.
+(defmacro with-out-str [& body]
+  `(__with-out-str (fn* [] ~@body)))
+
 ;; defmulti/defmethod are sugar over defmulti-setup/defmethod-setup (ctx-capturing
 ;; clojure.core fns) so they compile as plain invokes. name/mm are passed quoted;
 ;; the dispatch fn, options, and dispatch value evaluate normally, and the method
diff --git a/phase-5.md b/phase-5.md
deleted file mode 100644
index 1c117c2..0000000
--- a/phase-5.md
+++ /dev/null
@@ -1,439 +0,0 @@
-# Phase 5 — True Laziness (jolt-c09)
-
-Final phase of the `jolt-1j0` clojure.core migration epic. Make jolt's sequence
-generators and transformers genuinely lazy, so infinite seqs and lazy
-compositions work and stop hanging the evaluator. This is the deepest and
-riskiest phase — sub-stage it and gate every step.
-
-> Issue: `bd show jolt-c09`. Depends on Phase 4 (`jolt-ldf`, done). Blocks nothing
-> — it's the last phase.
-
----
-
-## 1. Current state (what already works, what doesn't)
-
-**The LazySeq machinery exists and is sound.** (`src/jolt/phm.janet`)
-- A LazySeq is `@{:jolt/type :jolt/lazy-seq :fn thunk :realized false :val nil}`.
-- A thunk returns `nil` (empty) or a cons cell `[first-val rest-thunk]`.
-- `realize-ls` forces one cell (memoized via `:realized`), with a `:jolt/pending`
-  sentinel that makes **self-referential** seqs work (`(def ones (lazy-seq (cons 1 ones)))`).
-- `ls-first` / `ls-rest` / `ls-seq` / `ls-count` walk it. `lazy-seq?` detects it.
-
-**Already lazy (keep):**
-- Infinite generators: `(range)`, `(repeat x)`, `(iterate f x)`, `(cycle ...)`,
-  `repeatedly` return LazySeq. Bounded forms (`(range n)`, `(repeat n x)`) are
-  eager tuples/arrays — correct, they're finite.
-- `map`/`filter` are **hybrid**: lazy when the input is a LazySeq, eager (and
-  representation-preserving) when the input is a concrete collection.
-- `take`/`drop`/`take-while` pull lazily from a LazySeq input but **return an eager
-  array** (fine for bounded `take`, wrong for the others on infinite tails).
-- Conformance already covers the working cases (self-ref fib, `iterate`, `count`
-  of `take`, `filter`/`take-while`/`remove` over `(range)`): see
-  `test/integration/conformance-test.janet` lines ~21–143.
-
-**The gaps (what hangs):**
-1. **Eager transformers that force their input** even when it's infinite. Confirmed
-   callers of `realize-for-iteration` in their bodies: `remove`, `interpose`,
-   `distinct`, `take-nth`, `map-indexed`, `keep-indexed`, `partition-all`,
-   `partition-by`, `drop-while`. Plus `partition`, `interleave`, `concat`,
-   `dedupe`, `flatten`, `tree-seq`, `mapcat`, `keep`, `sequence` need an
-   infinite-input audit.
-2. **`map`/`filter` over a *concrete vector* return an eager array**, not a lazy
-   seq. Clojure returns a lazy seq. This is a **representation decision** (§3 Step 6).
-3. **`realize-for-iteration` is the universal forcing point** (57 call sites). Many
-   are legitimate realization boundaries (`count`, `into`, `reduce`, `vec`, `pr`),
-   but any transformer that calls it on a lazy input loses laziness.
-4. **Evaluator eager assumptions** — the interpreter/compiler may realize seqs in
-   places (apply arg spreading, `doseq`, destructuring a seq). Audit needed.
-5. **CPU-bound hangs are uninterruptible.** An infinite realization is a tight
-   Janet loop with no yield points, so `ev/with-deadline` cannot truncate it
-   in-process — it pins the core. This is why the suite runs each file in a
-   **subprocess** (`os/spawn` + 6 s `ev/with-deadline`, then `os/proc-kill`). Phase
-   5 testing must do the same (see §7).
-
----
-
-## 2. Design principles (the cardinal rules)
-
-1. **A transformer never forces its input.** It returns a LazySeq whose thunk pulls
-   one element at a time via `core-first`/`core-rest`/`seq-done?`. No
-   `realize-for-iteration` inside a transformer.
-2. **Force only at realization boundaries.** Exactly the operations that *must* see
-   all elements: `pr`/`print`/`str` rendering, `=`, `count`, `reduce`, `into`,
-   `vec`/`seq`/`doall`, `doseq`, `nth`/`last` (these pull only as far as needed),
-   `apply` (spreads finitely). These are allowed to loop; on a genuinely infinite
-   seq they hang — matching Clojure.
-3. **One-element-at-a-time, memoized.** Reuse `make-lazy-seq`/`realize-ls`; never
-   re-walk. `realize-ls`'s `:jolt/pending` guard preserves self-reference.
-4. **Stack safety.** A chain of N lazy wrappers must not consume N stack frames per
-   element. Realize iteratively (a `while` over `realize-ls`), not by deep
-   recursion through `ls-rest`. Watch `concat`/`mapcat`/`lazy-cat` especially.
-5. **Multi-arity stays correct.** `map`/`mapcat` over multiple colls advance each
-   input one step per output element and stop at the shortest.
-
----
-
-## 3. Step-by-step implementation
-
-Order matters: build the helper layer, then convert transformers leaf-first, then
-fix boundaries, then the evaluator. Gate (§6) after **every** numbered step.
-
-### Step 0 — Safety net ✓ (commit e2e189a)
-- Record the baseline: conformance 229×3, clojure-test-suite `baseline-pass=3926`,
-  fixpoint stage1==2==3, self-host, all specs+unit, `lazy-seqs-spec` /
-  `sequences-spec` / `transducers-spec` green. ✓
-- Build the **infinite-seq harness** first (see §6.2, "Deadlined infinite-seq
-  spec") so every subsequent step is verified against hangs, not just values. ✓
-  → `test/support/lazy-eval.janet` (subprocess worker) +
-    `test/integration/lazy-infinite-test.janet` (os/spawn + 5s deadline)
-- Snapshot which clojure-test-suite files currently time out (the ~9). Save the
-  list — it's the acceptance target. ⚠ 9 files recorded but not yet re-verified post-conversion.
-
-### Step 1 — Lazy combinator layer ✓ (commit e2e189a)
-Add a small set of internal lazy builders so transformers compose uniformly,
-rather than each re-implementing the thunk dance:
-- `lazy-cons val thunk` → a LazySeq cell of `val` + a deferred rest. ✓
-  → `src/jolt/phm.janet` line 208; registered in core-bindings as `"lazy-cons"`.
-- `lazy-from coll` → coerce any seqable to a uniform lazy view *without forcing*
-  (vector/list/set/map/string/LazySeq → a LazySeq that pulls element by element).
-  This is the lazy analogue of `realize-for-iteration` and the key primitive: every
-  transformer takes `(lazy-from input)` and walks it with `core-first`/`core-rest`. ✓
-  → `src/jolt/core.janet` line 1112; registered in core-bindings as `"lazy-from"`.
-- `seq-done?` already exists — confirm it short-circuits without forcing the tail. ✓
-- Decide placement: the lazy machinery is host-coupled (Janet thunks) so it stays
-  in `phm.janet`/`core.janet`; transformers that are already in the overlay tiers
-  call these as primitives. ✓
-
-### Step 2 — Convert the core transformers (leaf-first) ✓ (commits e2e189a, d16e1f4, 97781b3, ff8ffb8)
-Make each return a LazySeq over `lazy-from input`. Do them in dependency order, one
-small batch per commit, each gated:
-- **2a. Single-input maps/filters:** `map` (1-coll) ✓ (already lazy), `filter` ✓ (already lazy),
-  `remove` ✓ (delegates to filter), `keep` ✓, `map-indexed` ✓, `keep-indexed` ✓,
-  `take-while` ✓ (already lazy), `drop-while` ✓, `take-nth` ✓.
-- **2b. Structural:** `cons` ✓ (already O(1) lazy cell), `rest`/`next` over lazy ✓,
-  `concat` ✓ + zero-arg returns @[], `lazy-cat` ✓ (verify), `mapcat` ✓ (standard
-  `(apply concat (apply map f colls))` + transducer arity. Lazy step-based overlay
-  attempted but **reverted** — compile-mode splice errors when used by defrecord's
-  `~@` syntax-quote. Needs Step 4 apply fix or defrecord rewrite),
-  `cycle` ✓ (already lazy), `interleave` ✓ (lazy multi-arity in overlay),
-  `interpose` ✓.
-- **2c. Windowing:** `partition` ✓, `partition-all` ✓, `partition-by` ⚠ (still eager),
-  `dedupe` ⚠ (still eager in overlay), `distinct` ✓, `take`/`drop` ⚠ (return
-  eager array, not LazySeq — representation decision, §3 Step 6).
-- **2d. Multi-input `map`/`mapcat`** over several colls (shortest-stops). ✓
-  → 9 new tests added to `sequences-spec.janet`, verified against Clojure & CLJS
-    reference implementations. Multi-input `map` already correct; `mapcat` uses
-    the standard overlay impl. No code changes needed.
-- **2e. Tree/seq:** `tree-seq` ⚠ (kept eager; lazy via mapcat triggers compile-mode
-  splice errors — documented with lazy version in comments), `flatten` ✓ (already
-  correct in overlay), `xml-seq` ✓ (added to overlay, matches Clojure),
-  `line-seq` ✓ (Janet stub — Java-specific API), `sequence` ✓ (Janet stub),
-  `iterator-seq` ✓ (Janet stub — Java-specific API),
-  `enumeration-seq` ✓ (Janet stub — Java-specific API).
-- For each: a transducer arity may exist (`td-*`) — leave it; only the
-  collection arity changes. ✓
-
-### Step 3 — Realization boundaries ✔ audit complete (documented in phase-5.md)
-
-Audit of 56 `realize-for-iteration` call sites in `src/jolt/core.janet` (excludes the definition at line 96). Each site classified below.
-
-#### Boundary (must force — correct)
-These functions require seeing all elements by contract.
-
-| Function | Line(s) | Why |
-|---|---|---|
-| `core-sqcat` | 136 | syntax-quote `~@` splicing — must flatten all parts |
-| `core-sqvec` | 141 | syntax-quote `[~@...]` — must flatten all parts |
-| `core-every?` | 205 | short-circuits on falsy but must iterate |
-| `eq-seqable` (part of `=`) | 258 | equality of lazy-seqs: must realize to compare elements |
-| `core-apply` | 506 | arg spread — forces final collection, matching Clojure |
-| `core-cons` | 626 | only reached for concrete non-lazy input; lazy already cell-based |
-| `core-vec` | 650 | builds a vector — must see all elements |
-| `core-select-keys` | 736 | filters keys from a collection |
-| `core-zipmap` | 742×2 | needs both key and value collections fully |
-| `reduce-with-reduced` | 821 | reduce must see all elements (set guard: concrete collections only) |
-| `core-into` | 847 | consumes entire collection into target |
-| `core-reduce` (3-arg) | 974 | must see all elements (set guard) |
-| `core-nth` (concrete) | 1199 | finite pull: must walk to index |
-| `core-take` (concrete) | 994 | finite prefix pull; could be element-at-a-time, but bounded |
-| `core-reverse` (concrete) | 1164 | reorder: must see all elements |
-| `core-sort` | 1212 | sorting: must see all elements |
-| `core-sort-by` | 1225 | sorting: must see all elements |
-| `core-set` | 1543 | builds a set — must see all elements |
-| `core-str-join` | 1670 | rendering: must see all elements |
-| `pr-render-seq` (in `str-render-one`) | 1626 | rendering lazy-seqs to strings |
-| `core-shuffle` | 2395 | reorder: must see all elements |
-| `core-doall` | 2540 | intentional realization — that's its purpose |
-| `core-dorun` | 2543 | intentional realization — that's its purpose |
-| `core-rand-nth` | 2558 | O(1) index into realized array |
-| `core-list*` | 2584 | splices final arg into preceding elements |
-| `core-transient` | 2631 | builds mutable copy from collection entries |
-| `core-hash-ordered-coll` | 2738 | hash computation: must see all elements |
-| `core-hash-unordered-coll` | 2740 | hash computation: must see all elements |
-| `core-chunk-cons` | 1841 | chunk helper — realizes chunk to concat |
-| `core-cat` | 1849 | transducer — must eat entire input element |
-| `core-mapcat` (transducer) | 1134 | transducer arity — internal to reducing fn |
-
-#### Conditional boundary (forces for concrete, lazy handled separately)
-These have a `(if (lazy-seq? coll) ...)` guard. The `realize-for-iteration` is only reached for concrete collections. Correct pattern.
-
-| Function | Line(s) | What happens for lazy input |
-|---|---|---|
-| `core-filter` | 951 | lazy branch: `fstep` walks lazily via `ls-first`/`ls-rest` |
-| `core-take-while` | 1037 | lazy branch: walks until pred fails |
-| `core-distinct` | 1254 | lazy branch: `dstep` yields one unique at a time |
-| `core-keep` | 2366 | lazy branch: `kstep` skips nils one element at a time |
-| `core-keep-indexed` | 1351 | lazy branch: `kstep` with index tracking |
-| `core-map-indexed` | 1366 | lazy branch: `mstep` pairs idx+val lazily |
-| `core-take-nth` | 2314 | lazy branch: `tstep` skips N elements at a time |
-| `core-interpose` | 2340 | lazy branch: `istep` alternates sep + element |
-| `core-partition-all` | 1324 | lazy branch: `pstep` pulls N elements at a time |
-| `core-partition` | 1285 | lazy branch: `pstep` with optional step parameter |
-| `core-drop` | 1013 | lazy branch: walks past N elements lazily |
-| `core-drop-while` | 1053 | lazy branch: `dwstep` skips past pred-matched elements |
-| `core-map` (single) | 880 | lazy branch: `mstep` maps one element at a time |
-
-#### Transformer leak (needs work — still forces)
-These functions call `realize-for-iteration` unconditionally on their input, breaking laziness. Each has a target Step for resolution.
-
-| Function | Line(s) | Severity | Target Step |
-|---|---|---|---|
-| `core-mapcat` (collection) | 1141 | HIGH | Step 4 — `apply` fix needed to avoid forcing `core-map` result. Currently `(apply concat ...)` forces via `realize-for-iteration`. Lazy overlay exists in `10-seq.clj` but reverted (compile-mode splice errors). |
-| `core-cycle` | 1372 | MED | Must snapshot input to cycle — would need a lazy cycling buffer. Low priority (cycle of finite coll). |
-| `core-partition-by` | 1299 | MED | Has no lazy branch yet. Needs Step 2c completion. |
-| `core-xml-seq` (Janet) | 2464 | LOW | **Overridden** by Clojure overlay `xml-seq` in `20-coll.clj` (uses `tree-seq`). The Janet stub remains for direct Janet-level callers but is rarely hit. Counted in Internal helpers below. |
-
-#### Interop helpers (context-dependent, keep)
-Array/byte conversion helpers that naturally force input.
-
-| Function | Line(s) | Why |
-|---|---|---|
-| `make-num-array` | 1769 | (T-array seq) — realizes seq to build native array |
-| `core-bytes` | 1784 | byte conversion — forces to encode bytes |
-| `core-into-array` | 1802 | realizes seq to build Java array |
-| `core-to-array` | 1805 | realizes seq to mutable array |
-| `core-to-array-2d` | 1807 | realizes 2-level seq to 2d array |
-
-#### Internal helpers (keep, context-dependent)
-| Function | Line(s) | Why |
-|---|---|---|
-| `core-map` multi-coll init | 894 | Pre-realizes concrete colls only; lazy colls go through step fn |
-| `core-map` multi-coll step | 919 | On-demand lazy pull: realizes concrete coll only when cursor exhausted |
-| `sorted-entries` | 2515 | Helper for `subseq`/`rsubseq`; forces sorted-coll items |
-| `core-xml-seq` (Janet, walk) | 2464 | Interim Janet impl — overridden by Clojure overlay xml-seq in 20-coll.clj |
-
-#### Summary
-
-| Category | Count |
-|---|---|
-| Boundary (correct) | 31 |
-| Conditional boundary (lazy branch exists) | 13 |
-| Transformer leak (needs work) | 3 |
-| Interop helper (keep) | 5 |
-| Internal helper (keep) | 4 |
-| **Total verified** | **56** |
-| **Leaks remaining** | **3 (mapcat, cycle, partition-by)** |
-
-Of the 3 leaks:
-- `mapcat` is the **critical remaining leak** — blocked on Step 4 `apply` fix.
-- `partition-by` and `cycle` are low-to-medium priority.
-- `xml-seq` Janet is **overridden** by the Clojure overlay — effectively resolved; counted in Internal helpers.
-
-### Step 4 — Evaluator / compiler eager assumptions
-Grep the interpreter (`src/jolt/evaluator.janet`) and back end
-(`src/jolt/backend.janet`, `compiler.janet`) for places that realize seqs:
-- `apply` / variadic arg spreading — must finitely spread, not realize an infinite
-  tail beyond the call.
-- `&`-rest binding in `fn*`/`let*`/`loop*` and `destructure` — a rest param over a
-  lazy seq should stay lazy, not eagerly slurp.
-- `doseq`/`for` desugaring (they go through `count`/`mapcat` — verify the `for`
-  comprehension stays lazy where Clojure's is).
-- Any `(each x (realize ...))` in hot paths that assumes finiteness.
-
-### Step 5 — Laziness-coupled stragglers (the deferred Phase-5 list)
-From `jolt-c09` notes / MIGRATION.md: `sequence`, `sequential?`, `seqable?`,
-`realized?`, `line-seq`, `rand-int`, `random-uuid`, `trampoline`, `unreduced`,
-`ensure-reduced`, the transducer machinery (`cat`, `eduction`, `transduce`,
-`sequence`, `halt-when`, `dedupe`/`interpose`/`keep` transducer arities). Move the
-now-lazy ones to the overlay where feasible (Phase-4 style), keeping the
-`Reduced`/thunk kernels native.
-
-### Step 6 — Representation decision ✅ Decided: Option A (full Clojure laziness)
-
-**Decision: Option A.** Lazy transformers always return a LazySeq, even over a
-concrete vector — matching Clojure: `(seq? (map inc [1 2 3]))` is **true**,
-`(vector? (map inc [1 2 3]))` is **false**.
-
-History: an earlier Option A attempt (commit a11535c, reverted) crashed
-(0/21 lazy-infinite, conformance crash) because flipping `map` to always-lazy
-without the supporting boundary fixes broke the `lazy-from → seq-done? →
-ls-first` chain. That measurement led to Option B (hybrid) and Phase 5 being
-declared complete.
-
-Option A was then re-attempted **with the boundary fixes the first attempt
-lacked**, and it works — all gates green (conformance 246×3, lazy-infinite
-40/40). The fixes that made it viable:
-- `cons` over a lazy-seq returns a LazySeq, not a raw `@[val thunk]` cell (a
-  cons-of-a-cons no longer leaks the rest-thunk as a list element).
-- `coll->cells` disambiguates cons cells (mutable arrays) from user vectors
-  whose 2nd element is a function (`[first last]`), and coerces set/map/string/
-  buffer via `core-seq`.
-- `core-nth`/`core-next`/`core-rest` walk lazy seqs via `seq-done?` (not element
-  truthiness or `length` on the lazy table), so a `false`/`nil` element isn't
-  mistaken for end-of-seq and `rest` never returns nil.
-- `~@` splice (interpreter `syntax-quote*`) and the test helper `normalize-pvecs`
-  realize lazy-seqs.
-- Transformers always route concrete input through `lazy-from` + the lazy step
-  machinery (dropping the eager `(if (jvec? coll) (make-vec …))` branch).
-
-All transformers are lazy in interpret/compile/self-host, using canonical
-recursive Clojure forms. (jolt-r81 — a compile-mode leak where lazy overlay fns
-returned the `lazy-seq` macro expansion as data — was root-fixed by moving
-`lazy-seq`/`lazy-cat` to the 00-syntax tier so they're registered before the
-seq/coll tiers that use them compile.)
-
----
-
-## 3b. Implementation notes (discovered during Phase 5)
-
-### mapcat + compile mode
-A lazy step-based `mapcat` (using `cons` + `lazy-seq` + recursive `fn` in the
-overlay) causes splice errors in self-hosted compilation. The `defrecord` macro
-in `30-macros.clj` uses `(vec (mapcat …))` inside syntax-quote, and `~@` cannot
-splice lazy-seqs. Reverted to the standard `(apply concat (apply map f colls))`
-implementation. Two possible fixes for the future:
-1. **Fix `apply` to spread lazy-seqs without forcing** (Step 4 proper) — the root cause.
-2. **Rewrite `defrecord`'s bind-generation to avoid `mapcat`** — replace
-   `(vec (mapcat (fn [f] …) fields))` with an eager `loop` accumulator.
-
-### tree-seq + compile mode
-Same root cause as mapcat: lazy `tree-seq` requires `mapcat` for
-`(when (branch? node) (mapcat walk (children node)))`. Kept eager; lazy version
-documented in `20-coll.clj` comments. Will switch when mapcat is resolved.
-
-### pre-existing: protocol-on-record compile-mode failure
-`(defprotocol P (m [_])) (defrecord R [side] P (m [_] (* side side))) (m (->R 4))`
-errors with "Unable to resolve symbol: side" in compile mode. This is a pre-existing
-issue unrelated to Phase 5 changes — `register-method` stores the method body as
-a raw `fn*` form, and the self-hosted compiler cannot resolve let-bound field
-access symbols at definition time (bindings only exist at call time).
-Conformance wraps this in `(= expected (do …))` so it's never triggered; only
-direct `eval-string` with `:compile? true` hits it. Not blocking — the
-self-host path (JOLT_SELFHOST=1) and interpret path both pass.
-
----
-
-## 4. Suggested commit cadence
-
-One transformer family (a §3 sub-step) per commit. Each commit:
-1. Convert the fns (overlay or core as appropriate).
-2. Add infinite-seq spec cases (§6.2) + value cases.
-3. Run the full gate (§6.1). Commit only if green. Push.
-
-Mirror the Phase 4 discipline: small, gated, reversible batches.
-
----
-
-## 5. Risks & gotchas
-
-- **Uninterruptible hangs:** never probe an infinite case in-process — it pins a
-  core and can't be killed by a deadline. Always go through the subprocess harness.
-- **Self-reference:** `(def s (lazy-seq (cons 1 s)))` and `lazy-cat` fib rely on
-  `realize-ls`'s `:jolt/pending` guard — don't bypass `realize-ls` with a
-  hand-rolled force.
-- **Stack overflow** from deep wrapper chains (`concat`/`mapcat`/`iterate` of
-  `iterate`) — realize iteratively.
-- **Double realization / side effects:** a lazy `map` fn with side effects must run
-  **once per element, in order, only when forced** — assert with a counter (§7).
-- **Performance:** LazySeq has per-element allocation + thunk-call overhead. Watch
-  `core-bench` (`test/bench/core-bench.janet`) — the eager fast paths exist partly
-  for speed. A heavy suite file slipping past the 6 s deadline = a regression
-  (this already bit Phase 3's macro move).
-- **Compile/self-host parity:** every behavior must hold in interpret, compile, and
-  self-host (conformance runs all three). Lazy thunks are closures — verify the
-  back end compiles them.
-- **`chunked` seqs are out of scope** — `chunked-seq?` stays `false`. Don't emulate
-  chunking; one-at-a-time is fine.
-
----
-
-## 6. Testing strategy
-
-### 6.1 Per-step gate (every commit) — same as Phase 4
-```
-janet test/integration/conformance-test.janet          # 229×3 (interpret/compile/self-host)
-janet test/integration/bootstrap-fixpoint-test.janet   # stage1==2==3
-janet test/integration/self-host-test.janet
-janet test/integration/sci-bootstrap-test.janet
-janet test/integration/clojure-test-suite-test.janet   # >= baseline (raise as it improves)
-for f in test/spec/*.janet test/unit/*.janet; do janet "$f"; done
-```
-
-### 6.2 Deadlined infinite-seq spec (the Phase-5-specific harness)
-Build this in Step 0. Plain in-process specs **cannot** test laziness — a wrong
-answer hangs instead of failing. Mirror `clojure-test-suite-test.janet`'s pattern:
-- A new `test/integration/lazy-infinite-test.janet` that, for each case, spawns a
-  worker (`os/spawn ["janet" "test/support/lazy-eval.janet" expr]`) and waits under
-  `(ev/with-deadline 5 (os/proc-wait proc))`, killing on timeout.
-- A timed-out or crashed case = **FAIL** (it should have produced a value).
-- Cases = the compositions that currently hang. Minimum set:
-  ```
-  (nth (map inc (range)) 1000)            => 1001
-  (first (filter even? (drop 3 (range)))) => 4
-  (take 3 (remove odd? (range)))          => (0 2 4)
-  (take 3 (drop-while #(< % 5) (range)))  => (5 6 7)
-  (take 4 (interleave (range) (iterate inc 10)))
-  (take 3 (partition 2 (range)))          => ((0 1) (2 3) (4 5))
-  (take 3 (partition-all 2 (range)))
-  (take 3 (map-indexed vector (range)))
-  (take 5 (distinct (cycle [1 2 1 3 1])))
-  (take 3 (mapcat (fn [x] [x x]) (range)))
-  (take 3 (take-nth 2 (range)))
-  (take 3 (interpose :x (range)))
-  (take 3 (map vector (range) (iterate inc 100)))
-  (second (cons :a (range)))
-  ```
-  Add one row per transformer converted in Step 2.
-
-### 6.3 Laziness assertions (side-effect counting)
-For each lazy transformer, assert it realizes **only what's demanded** — values
-alone don't prove laziness. Use a counter:
-```clojure
-(let [n (atom 0)]
-  (take 3 (map (fn [x] (swap! n inc) x) (range)))
-  @n)            ; => 3  (not "hang", not 1000)
-```
-Add these to `test/spec/lazy-seqs-spec.janet`. They run in-process safely because
-they only ever force a bounded prefix.
-
-### 6.4 Conformance extension
-Add infinite-composition rows to `conformance-test.janet` (runs ×3 modes) — the
-subset of §6.2 that returns a small concrete value, e.g.
-`["lazy compose" "(quote (1 3 5))" "(take 3 (filter odd? (map inc (range))))"]`.
-These guard interpret/compile/self-host parity.
-
-### 6.5 Acceptance target — the timed-out suite files
-The 9 files that currently time out (snapshot in Step 0:
-`cycle`/`range`/transducers-over-infinite tests) should stop timing out and start
-contributing passes. Each phase-5 step should monotonically reduce the timed-out
-count and **raise `baseline-pass`** in `clojure-test-suite-test.janet:35`. Final
-target: 0 (or near-0) timeouts and a meaningfully higher baseline.
-
-### 6.6 Regression guards
-- `core-bench` before/after (back-to-back, load-sensitive) — no large slowdown on
-  the eager-collection paths.
-- `lazy-seqs-spec`, `sequences-spec`, `transducers-spec` stay green every step.
-
----
-
-## 7. Done criteria
-
-- All §6.2 infinite-seq cases return correct values under the deadline (0 hangs). ✅ Done — 21/21
-- §6.3 laziness counters prove minimal realization for every converted transformer. ✅ Done — 16 counter tests added, all pass
-- Conformance 229+×3, fixpoint, self-host, sci-bootstrap all green. ✅ Done — 246/246 all three modes (Option A added cases)
-- clojure-test-suite: the ~9 infinite-seq files no longer time out; `baseline-pass`
-  raised to the new steady-state; no per-file 6 s timeouts introduced. ✅ Done — 3971 pass
-  (up from 3926), 6 timeouts (down from 9), 4628 assertions.
-- Representation decision (§3 Step 6, option A or B) documented and applied consistently. ✅ **Option A (full laziness)** — re-attempted with boundary fixes the first attempt lacked; all transformers lazy in 3 modes, conformance 246×3, lazy-infinite 40/40. (Earlier Option B was superseded.)
-- `core-bench` within noise of the Phase-4 baseline. ✅ Captured: TOTAL 2531 ms (fib 131, seq-pipe 97, reduce 414, into-vec 218, map-build 745, map-read 6, str-join 263, hof 657)
-- `bd close jolt-c09` → closes the `jolt-1j0` epic. ⚠ blocked on above
diff --git a/src/jolt/core.janet b/src/jolt/core.janet
index b94fd1e..cf089b8 100644
--- a/src/jolt/core.janet
+++ b/src/jolt/core.janet
@@ -269,7 +269,7 @@
 (defn core-max [& args] (each x args (need-num x "max")) (apply max args))
 (defn core-min [& args] (each x args (need-num x "min")) (apply min args))
 
-(defn core-rand [] (math/random))
+(defn core-rand [& n] (let [r (math/random)] (if (empty? n) r (* r (in n 0)))))
 (defn core-rand-int [n] (math/floor (* (math/random) n)))
 
 # ============================================================
@@ -375,12 +375,69 @@
 (defn- map-value? [x]
   (or (phm? x) (and (struct? x) (nil? (get x :jolt/type)))))
 
+# --- Sorted collections (sorted-map / sorted-set) -------------------------------
+# Defined here (before the collection fns) so conj/assoc/get/contains?/keys/vals/
+# disj can branch on them. A sorted-map is {:jolt/type :jolt/sorted-map :map STRUCT};
+# a sorted-set is {:jolt/type :jolt/sorted-set :items SORTED-ARRAY}. Keys/elements
+# are assumed Comparable scalars (the premise of a sorted coll); ops return a fresh
+# wrapper (persistent — source unchanged). A wrapper may carry an optional :cmp
+# (set by the by-comparator constructors) that all derived colls propagate.
+(defn core-sorted-map? [x] (and (table? x) (= :jolt/sorted-map (x :jolt/type))))
+(defn core-sorted-set? [x] (and (table? x) (= :jolt/sorted-set (x :jolt/type))))
+(defn core-sorted? [x] (or (core-sorted-map? x) (core-sorted-set? x)))
+# A sorted coll may carry a :cmp — a Janet 2-arg comparator returning a Clojure
+# compare result (neg/0/pos). nil means natural order (Janet's < via sort). The
+# by-comparator constructors install one (built from the user IFn); all derived
+# colls (assoc/conj/...) propagate it so ordering stays consistent.
+# A Clojure comparator is either a (neg/0/pos)-returning fn or a boolean predicate
+# (true => a sorts before b, like <). Reduce both to a strict less-than for sort.
+(defn- cmp-lt? [cmp a b]
+  (let [r (cmp a b)]
+    (if (boolean? r) r (if (number? r) (< r 0) (truthy? r)))))
+(defn- sorted-by [cmp arr] (if cmp (sort arr (fn [a b] (cmp-lt? cmp a b))) (sort arr)))
+(defn sm-make [m &opt cmp] @{:jolt/type :jolt/sorted-map :map m :cmp cmp})
+(defn ss-make [items &opt cmp] @{:jolt/type :jolt/sorted-set :items items :cmp cmp})
+(defn core-sorted-map [& kvs]
+  (var m @{}) (var i 0)
+  (while (< i (length kvs)) (put m (kvs i) (kvs (+ i 1))) (+= i 2))
+  (sm-make (table/to-struct m)))
+(defn core-sorted-set [& xs]
+  (var seen @{}) (each x xs (put seen x true))
+  (ss-make (sorted-by nil (array ;(keys seen)))))
+(defn sorted-map-keys [sm] (sorted-by (sm :cmp) (array ;(keys (sm :map)))))
+(defn sorted-map-entries [sm] (let [m (sm :map)] (map (fn [k] [k (get m k)]) (sorted-map-keys sm))))
+(defn sm-assoc-many [sm kvs]
+  (var m @{}) (each k (keys (sm :map)) (put m k (get (sm :map) k)))
+  (var i 0) (while (< i (length kvs)) (put m (kvs i) (kvs (+ i 1))) (+= i 2))
+  (sm-make (table/to-struct m) (sm :cmp)))
+(defn sm-dissoc-many [sm ks]
+  (def rm @{}) (each x ks (put rm x true))
+  (var m @{}) (each k (keys (sm :map)) (unless (get rm k) (put m k (get (sm :map) k))))
+  (sm-make (table/to-struct m) (sm :cmp)))
+(defn ss-contains? [ss x] (var f false) (each e (ss :items) (when (deep= e x) (set f true) (break))) f)
+(defn ss-conj-many [ss xs]
+  (var seen @{}) (each e (ss :items) (put seen e true)) (each x xs (put seen x true))
+  (ss-make (sorted-by (ss :cmp) (array ;(keys seen))) (ss :cmp)))
+(defn ss-disj-many [ss xs]
+  (def rm @{}) (each x xs (put rm x true))
+  (ss-make (filter (fn [e] (not (get rm e))) (ss :items)) (ss :cmp)))
+
 (defn core-conj [& args]
   (if (= 0 (length args)) (make-vec @[])        # (conj) -> []
   (let [coll (first args) xs (tuple/slice args 1)]
   (if (nil? coll)
     # conj onto nil builds a list (prepends): (conj nil 1 2) -> (2 1)
     (do (var result nil) (each x xs (set result (pl-cons x result))) result)
+  (if (core-sorted-map? coll)
+    # conj a [k v] entry (or merge a map) into a sorted-map
+    (do (var m coll)
+      (each x xs
+        (if (map-value? x)
+          (each e (map-entries-of x) (set m (sm-assoc-many m [(in e 0) (in e 1)])))
+          (set m (sm-assoc-many m [(vnth x 0) (vnth x 1)]))))
+      m)
+  (if (core-sorted-set? coll)
+    (ss-conj-many coll xs)
   (if (pvec? coll)
     (do (var result coll) (each x xs (set result (pv-conj result x))) result)
   (if (plist? coll)
@@ -414,7 +471,7 @@
                 (each e (map-entries-of x)
                   (set result (map-assoc1 result (in e 0) (in e 1))))
                 (set result (map-assoc1 result (vnth x 0) (vnth x 1)))))
-            result)))))))))))
+            result)))))))))))))
 
 (defn core-assoc [m & kvs]
   (when (odd? (length kvs))
@@ -425,6 +482,7 @@
             (and (struct? m) (get m :jolt/type)))
     (error (string "assoc requires a map or vector, got " (type m))))
   (cond
+    (core-sorted-map? m) (sm-assoc-many m kvs)
     (phm? m)
       (do (var result m) (var i 0) (while (< i (length kvs)) (set result (phm-assoc result (kvs i) (kvs (+ i 1)))) (+= i 2)) result)
     (pvec? m)
@@ -466,6 +524,7 @@
 (defn core-dissoc [m & ks]
   (cond
     (nil? m) nil
+    (core-sorted-map? m) (sm-dissoc-many m ks)
     (phm? m) (do (var result m) (each k ks (set result (phm-dissoc result k))) result)
     # reject clearly non-map values (scalars, sequences, sets, symbol/char structs)
     (or (number? m) (string? m) (buffer? m) (keyword? m) (boolean? m)
@@ -479,6 +538,8 @@
 (defn core-get [m k &opt default]
   (default default nil)
   (if (nil? m) default
+    (if (core-sorted-map? m) (let [v (get (m :map) k)] (if (nil? v) default v))
+    (if (core-sorted-set? m) (if (ss-contains? m k) k default)
     (if (core-transient? m)
       (case (m :kind)
         :vector (if (and (number? k) (>= k 0) (< k (length (m :arr)))) (in (m :arr) k) default)
@@ -493,7 +554,7 @@
             (if (nil? v) default v))
           (if (and (or (tuple? m) (array? m)) (number? k) (>= k 0) (< k (length m)))
             (in m k)
-            default))))))))
+            default))))))))))
 
 # Runtime invoke dispatch for COMPILED code (interpreter uses evaluator's
 # jolt-invoke). Handles real functions plus Clojure IFn collections.
@@ -502,6 +563,8 @@
     (or (function? f) (cfunction? f)) (apply f args)
     (keyword? f) (core-get (get args 0) f (get args 1))
     (and (struct? f) (= :symbol (f :jolt/type))) (core-get (get args 0) f (get args 1))
+    (core-sorted-map? f) (let [v (get (f :map) (get args 0))] (if (nil? v) (get args 1) v))
+    (core-sorted-set? f) (if (ss-contains? f (get args 0)) (get args 0) (get args 1))
     (phm? f) (phm-get f (get args 0) (get args 1))
     (set? f) (if (phs-contains? f (get args 0)) (get args 0) (get args 1))
     (pvec? f)
@@ -551,6 +614,8 @@
   (if missing default current))
 
 (defn core-contains? [coll key]
+  (if (core-sorted-map? coll) (not (nil? (get (coll :map) key)))
+  (if (core-sorted-set? coll) (ss-contains? coll key)
   (if (core-transient? coll)
     (case (coll :kind)
       :vector (and (number? key) (>= key 0) (< key (length (coll :arr))))
@@ -562,7 +627,7 @@
         (if (table? coll) (not (nil? (coll key)))
           (if (or (tuple? coll) (array? coll))
             (and (number? key) (>= key 0) (< key (length coll)))
-            false))))))))
+            false))))))))))
 
 # Coerce a Clojure IFn value to a Janet-callable fn for higher-order fns
 # (map/filter/sort-by/group-by/...). Janet functions pass through; a keyword or
@@ -579,19 +644,8 @@
 
 # Sorted collections — minimal: backed by a struct (map) / sorted array (set),
 # ordered by key/element on read. Defined early so seq/count/get can dispatch.
-(defn core-sorted-map? [x] (and (table? x) (= :jolt/sorted-map (x :jolt/type))))
-(defn core-sorted-set? [x] (and (table? x) (= :jolt/sorted-set (x :jolt/type))))
-(defn sm-make [m] @{:jolt/type :jolt/sorted-map :map m})
-(defn ss-make [items] @{:jolt/type :jolt/sorted-set :items items})
-(defn core-sorted-map [& kvs]
-  (var m @{}) (var i 0)
-  (while (< i (length kvs)) (put m (kvs i) (kvs (+ i 1))) (+= i 2))
-  (sm-make (table/to-struct m)))
-(defn core-sorted-set [& xs]
-  (var seen @{}) (each x xs (put seen x true))
-  (ss-make (sort (array ;(keys seen)))))
-(defn sorted-map-keys [sm] (sort (array ;(keys (sm :map)))))
-(defn sorted-map-entries [sm] (let [m (sm :map)] (map (fn [k] [k (get m k)]) (sorted-map-keys sm))))
+# sorted-map/sorted-set predicates, constructors and ops live ABOVE core-conj so
+# the collection fns (conj/assoc/get/contains?/…) can branch on them.
 
 (defn core-count [coll]
   (cond
@@ -771,10 +825,12 @@
 
 (defn core-keys [m]
   # phm-entries (not phm-to-struct) so keys mapped to nil values are not dropped.
-  (if (phm? m) (tuple ;(map |(in $ 0) (phm-entries m))) (tuple ;(keys m))))
+  (if (core-sorted-map? m) (tuple ;(sorted-map-keys m))
+  (if (phm? m) (tuple ;(map |(in $ 0) (phm-entries m))) (tuple ;(keys m)))))
 
 (defn core-vals [m]
-  (if (phm? m) (tuple ;(map |(in $ 1) (phm-entries m))) (tuple ;(map |(m $) (keys m)))))
+  (if (core-sorted-map? m) (tuple ;(map |(in $ 1) (sorted-map-entries m)))
+  (if (phm? m) (tuple ;(map |(in $ 1) (phm-entries m))) (tuple ;(map |(m $) (keys m))))))
 
 (defn core-select-keys [m ks]
   # Include a key when it is PRESENT (contains?), even if its value is nil — a
@@ -1507,7 +1563,10 @@
 
 (defn core-set? [x] (set? x))
 (defn core-disj [s & ks]
-  (if (set? s) (apply phs-disj s ks) (error "disj expects a set")))
+  (cond
+    (core-sorted-set? s) (ss-disj-many s ks)
+    (set? s) (apply phs-disj s ks)
+    (error "disj expects a set")))
 
 (defn core-set [coll]
   (apply core-hash-set (realize-for-iteration coll)))
@@ -1696,6 +1755,14 @@
   (prin "\n")
   nil)
 
+# Capture *out*: run thunk with Janet's :out dynamic bound to a buffer, so all
+# print/println/pr/prn output (which go through `prin` -> (dyn :out)) is collected
+# and returned as a string. The with-out-str macro (overlay) wraps a body thunk.
+(defn core-with-out-str [thunk]
+  (def buf @"")
+  (with-dyns [:out buf] (thunk))
+  (string buf))
+
 (defn core-pr [& xs]
   (var i 0)
   (while (< i (length xs))
@@ -1824,8 +1891,17 @@
 (defn core-reader-conditional [form splicing?]
   @{:jolt/type :jolt/reader-conditional :form form :splicing? splicing?})
 # reader-conditional? now lives in the Clojure collection tier (tagged-value predicate).
-(defn core-sorted-map-by [cmp & kvs] (apply core-sorted-map kvs))
-(defn core-sorted-set-by [cmp & xs] (apply core-sorted-set xs))
+# The user comparator is a Clojure IFn; wrap it as a Janet 2-arg fn returning the
+# numeric compare result, then thread it through the sorted wrapper.
+(defn core-sorted-map-by [cmp & kvs]
+  (let [jc (fn [a b] (jolt-call cmp a b))]
+    (var m @{}) (var i 0)
+    (while (< i (length kvs)) (put m (kvs i) (kvs (+ i 1))) (+= i 2))
+    (sm-make (table/to-struct m) jc)))
+(defn core-sorted-set-by [cmp & xs]
+  (let [jc (fn [a b] (jolt-call cmp a b))]
+    (var seen @{}) (each x xs (put seen x true))
+    (ss-make (sorted-by jc (array ;(keys seen))) jc)))
 (defn core-array-seq [arr & _] (core-seq arr))
 (defn core-seque [& args] (in args (- (length args) 1)))
 (defn core-supers [x] (make-phs))
@@ -1964,6 +2040,8 @@
 # future macro: (future body...) -> (future-call (fn* [] body...))
 (defn core-deref [ref & opts]
   (cond
+    (and (table? ref) (= :jolt/reduced (ref :jolt/type)))
+    (ref :val)
     (and (table? ref) (= :jolt/atom (ref :jolt/type)))
     (ref :value)
     (and (table? ref) (= :jolt/volatile (ref :jolt/type)))
@@ -2828,7 +2906,7 @@
     "namespace" core-namespace
     "sorted-map" core-sorted-map
     "sorted-set" core-sorted-set
-    "sorted?" core-sorted-map?
+    "sorted?" core-sorted?
     "reduced" core-reduced
     "reduced?" core-reduced?
     "take-nth" core-take-nth
@@ -2842,6 +2920,7 @@
     "ex-info" core-ex-info
     "prn-str" core-prn-str
     "println-str" core-println-str
+    "__with-out-str" core-with-out-str
     "force" core-force
     "realized?" core-realized?
     "delay?" core-delay?
diff --git a/src/jolt/evaluator.janet b/src/jolt/evaluator.janet
index 099ced6..dcef376 100644
--- a/src/jolt/evaluator.janet
+++ b/src/jolt/evaluator.janet
@@ -102,6 +102,10 @@
     (keyword? f) (coll-lookup (get args 0) f (get args 1))
     (and (struct? f) (= :symbol (f :jolt/type)))
       (coll-lookup (get args 0) f (get args 1))
+    (and (table? f) (= :jolt/sorted-map (f :jolt/type)))
+      (let [v (get (f :map) (get args 0))] (if (nil? v) (get args 1) v))
+    (and (table? f) (= :jolt/sorted-set (f :jolt/type)))
+      (if (some |(deep= $ (get args 0)) (f :items)) (get args 0) (get args 1))
     (phm? f) (phm-get f (get args 0) (get args 1))
     (set? f) (if (phs-contains? f (get args 0)) (get args 0) (get args 1))
     (pvec? f)
@@ -149,7 +153,8 @@
                        :name (string (string/slice nm 0 -2) "__" (string (gensym)) "__auto")}]
                 (put gsmap nm g) g))
         (special-symbol? nm) form
-        (ns-find (ctx-find-ns ctx "clojure.core") nm) form
+        (ns-find (ctx-find-ns ctx "clojure.core") nm)
+          {:jolt/type :symbol :ns "clojure.core" :name nm}
         {:jolt/type :symbol :ns (ctx-current-ns ctx) :name nm}))
     form))
 
@@ -266,9 +271,13 @@
   [ctx bindings sym-s]
   (let [name (sym-s :name) ns (sym-s :ns)]
     (if (not (nil? ns))
-      # Resolve ns aliases (e.g. `p/thrown?` where `p` is a require :as alias)
-      # so that aliased macros are recognized as macros, matching resolve-sym.
-      (let [current-ns (ctx-find-ns ctx (ctx-current-ns ctx))
+      # Resolve ns aliases (e.g. `p/thrown?` where `p` is a require :as alias) so
+      # aliased refs/macros resolve. During compilation the analyzer (interpreted,
+      # in jolt.analyzer) rebinds ctx-current-ns to its own ns, so look up the alias
+      # against the COMPILE ns (:compile-ns, the user's ns) when set — otherwise an
+      # aliased ref like g/foo wouldn't resolve mid-compile. Same ns h-current-ns uses.
+      (let [cur-name (or (get (ctx :env) :compile-ns) (ctx-current-ns ctx))
+            current-ns (ctx-find-ns ctx cur-name)
             aliased-ns (ns-import-lookup current-ns ns)
             target-ns (ctx-find-ns ctx (or aliased-ns ns))]
         (ns-find target-ns name))
diff --git a/test/integration/features-test.janet b/test/integration/features-test.janet
index 7785451..2548956 100644
--- a/test/integration/features-test.janet
+++ b/test/integration/features-test.janet
@@ -82,7 +82,8 @@
    ["macroexpand-1"      "true"        "(do (defmacro mm [x] (list 'inc x)) (= '(inc 5) (macroexpand-1 '(mm 5))))"]
    ["gensym distinct"    "false"       "(= (gensym) (gensym))"]
    ["syntax-quote splice" "[1 2 3]" "(let [xs [1 2 3]] `[~@xs])"]
-   ["syntax-quote unquote" "(quote (+ 1 5))" "(let [x 5] `(+ 1 ~x))"]
+   # syntax-quote fully-qualifies resolved core symbols to clojure.core/ (jolt-265).
+   ["syntax-quote unquote" "(quote (clojure.core/+ 1 5))" "(let [x 5] `(+ 1 ~x))"]
 
    ### 8. Recursion
    ["recursion fact"     "120"         "(do (defn fact [n] (if (<= n 1) 1 (* n (fact (dec n))))) (fact 5))"]
diff --git a/test/spec/io-spec.janet b/test/spec/io-spec.janet
new file mode 100644
index 0000000..73d017f
--- /dev/null
+++ b/test/spec/io-spec.janet
@@ -0,0 +1,26 @@
+# Specification: printing / output (print/println/pr/prn, *-str, format, str).
+# Output is captured with with-out-str (jolt-rfw); the *-str fns return strings.
+(use ../support/harness)
+
+(defspec "io / with-out-str captures"
+  ["println"         "\"hi\\n\""   "(with-out-str (println \"hi\"))"]
+  ["print spaces"    "\"a b\""     "(with-out-str (print \"a\" \"b\"))"]
+  ["prn quotes"      "\"[1 2]\\n\"" "(with-out-str (prn [1 2]))"]
+  ["pr no newline"   "\"5\""       "(with-out-str (pr 5))"]
+  ["multiple writes" "\"12\""      "(with-out-str (print 1) (print 2))"]
+  ["no output"       "\"\""        "(with-out-str 42)"]
+  ["println no args" "\"\\n\""     "(with-out-str (println))"])
+
+(defspec "io / *-str builders"
+  ["print-str"       "\"a b\""     "(print-str \"a\" \"b\")"]
+  ["println-str"     "\"x\\n\""    "(println-str \"x\")"]
+  ["prn-str"         "\"[1 2]\\n\"" "(prn-str [1 2])"]
+  ["pr-str quotes"   "\"\\\"s\\\"\"" "(pr-str \"s\")"]
+  ["pr-str keyword"  "\":a\""      "(pr-str :a)"])
+
+(defspec "io / str & format"
+  ["str concat"      "\"1:ab\""    "(str 1 :a \"b\")"]
+  ["str nil"         "\"\""        "(str nil)"]
+  ["str of coll"     "\"[1 2]\""   "(str [1 2])"]
+  ["format d/s"      "\"5-x\""     "(format \"%d-%s\" 5 \"x\")"]
+  ["format float"    "\"3.14\""    "(format \"%.2f\" 3.14159)"])
diff --git a/test/spec/numbers-spec.janet b/test/spec/numbers-spec.janet
index 54f32cc..9ed49a7 100644
--- a/test/spec/numbers-spec.janet
+++ b/test/spec/numbers-spec.janet
@@ -126,3 +126,11 @@
   ["bit-clear"          "13"     "(bit-clear 15 1)"]
   ["bit-test true"      "true"   "(bit-test 4 2)"]
   ["bigint 64-bit"      "\"9000000000\"" "(str (bigint 9000000000))"])
+
+(defspec "numbers / random (invariants — non-deterministic)"
+  ["rand-int in range"  "true" "(let [r (rand-int 5)] (and (integer? r) (>= r 0) (< r 5)))"]
+  ["rand-int zero"      "0"    "(rand-int 1)"]
+  ["rand in [0,1)"      "true" "(let [r (rand)] (and (>= r 0) (< r 1)))"]
+  ["rand n in [0,n)"    "true" "(let [r (rand 10)] (and (>= r 0) (< r 10)))"]
+  ["rand-nth member"    "true" "(contains? #{:a :b :c} (rand-nth [:a :b :c]))"]
+  ["rand-nth single"    ":x"   "(rand-nth [:x])"])
diff --git a/test/spec/predicates-spec.janet b/test/spec/predicates-spec.janet
index fd8ea0a..e1a860c 100644
--- a/test/spec/predicates-spec.janet
+++ b/test/spec/predicates-spec.janet
@@ -113,3 +113,20 @@
   ["not= differs"       "true"   "(not= [1 2] [1 3])"]
   ["identical? same kw" "true"   "(identical? :a :a)"]
   ["compare strings"    "-1"     "(compare \"a\" \"b\")"])
+
+(defspec "predicates / seqable, reduced & emptiness"
+  ["seqable? vector"   "true"   "(seqable? [1])"]
+  ["seqable? map"      "true"   "(seqable? {:a 1})"]
+  ["seqable? string"   "true"   "(seqable? \"s\")"]
+  ["seqable? nil"      "true"   "(seqable? nil)"]
+  ["seqable? number"   "false"  "(seqable? 5)"]
+  ["integer? int"      "true"   "(integer? 5)"]
+  ["integer? fraction" "false"  "(integer? 5.5)"]
+  ["reduced? wrapped"  "true"   "(reduced? (reduced 1))"]
+  ["reduced? plain"    "false"  "(reduced? 1)"]
+  ["deref reduced"     "9"      "(deref (reduced 9))"]
+  ["unreduced wrapped" "9"      "(unreduced (reduced 9))"]
+  ["unreduced plain"   "9"      "(unreduced 9)"]
+  ["not-empty full"    "[1]"    "(not-empty [1])"]
+  ["not-empty empty"   "nil"    "(not-empty [])"]
+  ["not-empty string"  "nil"    "(not-empty \"\")"])
diff --git a/test/spec/reader-forms-spec.janet b/test/spec/reader-forms-spec.janet
index 3022c59..aa4bf19 100644
--- a/test/spec/reader-forms-spec.janet
+++ b/test/spec/reader-forms-spec.janet
@@ -38,12 +38,12 @@
   ["gensym distinct" "true"   "(not= `meow# `meow#)"]
   ["gensym stable"   "true"   "(let [s `[meow# meow#]] (= (first s) (second s)))"]
   ["qualifies unresolved" "(quote user/foo)" "`foo"]
+  # jolt-265 (fixed): resolved core symbols fully-qualify to clojure.core/.
+  ["qualifies core sym" "(quote clojure.core/str)" "`str"]
   ["unquote value"   "[1 2 3]" "(let [a [1 2 3]] `~a)"]
-  # functional: the syntax-quoted call evaluates correctly. (jolt-265: core syms are
-  # left bare rather than qualified to clojure.core/ — full qualification breaks the
-  # standalone uberscript's ns macro, so it's deferred; they still resolve at eval.)
-  ["unquote call evals" "6" "(let [a 5] (eval `(+ ~a 1)))"]
-  ["splice call evals" "6"  "(let [a [1 2 3]] (eval `(+ ~@a)))"]
+  ["unquote in call" "(quote (clojure.core/str [1 2 3]))" "(let [a [1 2 3]] `(str ~a))"]
+  ["splice empty"    "(quote (clojure.core/str))" "(let [e []] `(str ~@e))"]
+  ["splice values"   "(quote (clojure.core/str 1 2 3))" "(let [a [1 2 3]] `(str ~@a))"]
   ["splice in vector" "[1 2 3 0 1 2 3]" "(let [b [0] a [1 2 3] e []] `[~@e ~@a ~@b ~@a ~@e])"]
   # jolt-edb (fixed): ~/~@ inside set literals.
   ["splice in set"   "#{0 1 2 3}" "(let [b [0] a [1 2 3] e []] `#{~@e ~@a ~@b})"]
diff --git a/test/spec/regex-spec.janet b/test/spec/regex-spec.janet
new file mode 100644
index 0000000..15b3b8e
--- /dev/null
+++ b/test/spec/regex-spec.janet
@@ -0,0 +1,33 @@
+# Specification: regular expressions — #"…" literals and the re-* fns.
+# (Whole area previously unspecced; some cases adapted from jank reader-macro/regex.)
+(use ../support/harness)
+
+(defspec "regex / literals & predicate"
+  ["regex? literal"   "true"   "(regex? #\"\\d+\")"]
+  ["regex? non-regex" "false"  "(regex? \"\\d+\")"]
+  ["escaped digits"   "\"42\"" "(re-find #\"\\d+\" \"x42y\")"]
+  ["escaped ws/non-ws" "\"x a\"" "(re-find #\"\\S\\s\\S\" \"x a b y\")"])
+
+(defspec "regex / re-find"
+  ["match"            "\"123\"" "(re-find #\"\\d+\" \"abc123def\")"]
+  ["no match nil"     "nil"    "(re-find #\"\\d+\" \"abc\")"]
+  ["with groups"      "[\"a1\" \"a\" \"1\"]" "(re-find #\"([a-z])(\\d)\" \"--a1--\")"]
+  ["first match only" "\"1\""  "(re-find #\"\\d\" \"1 2 3\")"])
+
+(defspec "regex / re-matches"
+  ["full match"       "\"123\"" "(re-matches #\"\\d+\" \"123\")"]
+  ["partial = nil"    "nil"    "(re-matches #\"\\d+\" \"123abc\")"]
+  ["groups"           "[\"12\" \"1\" \"2\"]" "(re-matches #\"(\\d)(\\d)\" \"12\")"]
+  ["no match nil"     "nil"    "(re-matches #\"x+\" \"yyy\")"])
+
+(defspec "regex / re-seq"
+  ["all matches"      "(quote (\"1\" \"22\" \"333\"))" "(re-seq #\"\\d+\" \"a1b22c333\")"]
+  ["empty when none"  "nil"    "(seq (re-seq #\"z\" \"abc\"))"]
+  ["words"            "(quote (\"foo\" \"bar\"))" "(re-seq #\"\\w+\" \"foo bar\")"])
+
+(defspec "regex / re-pattern & string ops"
+  ["re-pattern build" "\"hi\"" "(re-find (re-pattern \"\\\\w+\") \"hi!\")"]
+  ["re-pattern is regex?" "true" "(regex? (re-pattern \"a\"))"]
+  ["split on regex"   "[\"a\" \"b\" \"c\"]" "(do (require '[clojure.string :as s]) (s/split \"a1b2c\" #\"\\d\"))"]
+  ["replace regex"    "\"X-X\"" "(do (require '[clojure.string :as s]) (s/replace \"a-b\" #\"[a-z]\" \"X\"))"]
+  ["replace $1"       "\"[a][b]\"" "(do (require '[clojure.string :as s]) (s/replace \"ab\" #\"([a-z])\" \"[$1]\"))"])
diff --git a/test/spec/sorted-spec.janet b/test/spec/sorted-spec.janet
new file mode 100644
index 0000000..4224d59
--- /dev/null
+++ b/test/spec/sorted-spec.janet
@@ -0,0 +1,59 @@
+# Specification: sorted collections (sorted-map / sorted-set, subseq/rsubseq).
+#
+# sorted collections are first-class for the core ops (jolt-ti9): get/assoc/dissoc/
+# conj/contains?/keys/vals/disj all work and preserve sort order, and a sorted coll
+# is callable as a key-lookup fn. STILL TODO: the by-comparator constructors
+# (sorted-map-by / sorted-set-by) ignore the supplied comparator (jolt-ti9). (vec
+# coerces a seq to a vector so expecteds are vector literals, not quoted lists.)
+(use ../support/harness)
+
+(defspec "sorted / construction & ordering"
+  ["sorted-set orders"   "[1 2 3]" "(vec (seq (sorted-set 3 1 2)))"]
+  ["sorted-set dedupes"  "[1 2 3]" "(vec (seq (sorted-set 3 1 2 1 3)))"]
+  ["sorted-set numeric"  "[1 2 10]" "(vec (seq (sorted-set 10 1 2)))"]
+  ["sorted-map ordered entries" "[[:a 1] [:b 2] [:c 3]]" "(vec (seq (sorted-map :c 3 :a 1 :b 2)))"]
+  ["first is min"        "1"       "(first (sorted-set 5 3 9 1))"])
+
+(defspec "sorted / sorted?"
+  ["sorted-set"      "true"   "(sorted? (sorted-set 1))"]
+  ["sorted-map"      "true"   "(sorted? (sorted-map :a 1))"]
+  ["plain set"       "false"  "(sorted? #{1})"]
+  ["plain map"       "false"  "(sorted? {:a 1})"]
+  ["vector"          "false"  "(sorted? [1 2])"])
+
+(defspec "sorted / map ops"
+  ["get hit"         "2"        "(get (sorted-map :a 1 :b 2) :b)"]
+  ["get miss default" ":none"   "(get (sorted-map :a 1) :z :none)"]
+  ["contains? yes"   "true"     "(contains? (sorted-map :a 1) :a)"]
+  ["contains? no"    "false"    "(contains? (sorted-map :a 1) :z)"]
+  ["assoc keeps order" "[[:a 1] [:b 2] [:c 3]]" "(vec (seq (assoc (sorted-map :c 3 :a 1) :b 2)))"]
+  ["dissoc"          "[[:a 1] [:c 3]]" "(vec (seq (dissoc (sorted-map :a 1 :b 2 :c 3) :b)))"]
+  ["conj entry"      "[[:a 1] [:z 9]]" "(vec (seq (conj (sorted-map :a 1) [:z 9])))"]
+  ["keys sorted"     "[:a :b :c]" "(vec (keys (sorted-map :c 3 :a 1 :b 2)))"]
+  ["vals by key"     "[1 2 3]"  "(vec (vals (sorted-map :c 3 :a 1 :b 2)))"]
+  ["map as fn"       "2"        "((sorted-map :a 1 :b 2) :b)"]
+  ["map as fn miss"  ":d"       "((sorted-map :a 1) :z :d)"])
+
+(defspec "sorted / set ops"
+  ["get present"     "2"        "(get (sorted-set 1 2 3) 2)"]
+  ["get absent"      ":none"    "(get (sorted-set 1 2 3) 9 :none)"]
+  ["contains? yes"   "true"     "(contains? (sorted-set 1 2 3) 2)"]
+  ["contains? no"    "false"    "(contains? (sorted-set 1 2 3) 9)"]
+  ["conj keeps order" "[0 1 2 3 5]" "(vec (seq (conj (sorted-set 1 2 3) 5 0)))"]
+  ["disj"            "[1 3]"    "(vec (seq (disj (sorted-set 1 2 3) 2)))"]
+  ["set as fn"       "3"        "((sorted-set 1 2 3) 3)"]
+  ["set as fn miss"  "nil"      "((sorted-set 1 2 3) 9)"])
+
+(defspec "sorted / by comparator"
+  ["sorted-set-by desc"  "[10 3 2 1]" "(vec (seq (sorted-set-by > 1 3 2 10)))"]
+  ["sorted-map-by desc"  "[[3 :c] [2 :b] [1 :a]]" "(vec (seq (sorted-map-by > 1 :a 3 :c 2 :b)))"]
+  ["conj keeps comparator" "[5 3 2 1 0]" "(vec (seq (conj (sorted-set-by > 1 3 2) 5 0)))"]
+  ["assoc keeps comparator" "[3 2 1]" "(vec (keys (assoc (sorted-map-by > 1 :a 3 :c) 2 :b)))"]
+  ["disj keeps comparator" "[3 1]"   "(vec (seq (disj (sorted-set-by > 1 2 3) 2)))"]
+  ["by-comparator is sorted?" "true" "(sorted? (sorted-set-by > 1 2))"])
+
+(defspec "sorted / subseq & rsubseq"
+  ["subseq >="       "[3 4 5]" "(vec (subseq (sorted-set 1 2 3 4 5) >= 3))"]
+  ["subseq <"        "[1 2]"   "(vec (subseq (sorted-set 1 2 3 4 5) < 3))"]
+  ["subseq range"    "[2 3 4]" "(vec (subseq (sorted-set 1 2 3 4 5) > 1 < 5))"]
+  ["rsubseq <="      "[3 2 1]" "(vec (rsubseq (sorted-set 1 2 3 4 5) <= 3))"])