Runtime baseline — RUN AGS-20260821-sequentialthinking

Logical record 5. Mandatory; run before lens applicability was decided. IDs are those registered in evidence-packet.md §4.

5.1 Causal responsibilities, not module boundaries

Three causal responsibilities are traced: scheduling, context assembly, and external state/action. In this system they do not map to three modules — two of them are almost entirely absent from the boundary, and the third is concentrated in one method.

Responsibility Where it lives inside the boundary Where it actually lives
Scheduling nowhere (ABS-7) entirely in the host + model, outside the boundary
Context assembly RTE-2 (descriptor out) and RTE-9 (response out) — the server contributes two fixed-shape payloads and selects nothing assembly proper is the host's; the server has no selection policy
External state / action RTE-6, RTE-7 (in-process writes) and RTE-8 (stderr) only; no external effect (ABS-2) —

One facility, CMP-8 processThought, spans validation dispatch, content update, both state writes, the observability action, and response construction. It is a single method, ~45 lines, and is the whole material path.

5.2 Material loops

A loop is material when it alters the analysis question, a control path, evidence strength, or a lens result. Three loops qualify; each is recorded against the full field set.

Loop A — server lifecycle (RTE-1, RTE-12)

Field Record Evidence
Trigger / input host spawns the process (typically npx -y @modelcontextprotocol/server-sequential-thinking, RTE-13); no arguments are read (ABS-1) SRC-1:269-278, SRC-2:47-59
Next-step owner the SDK's stdio read loop (SRC-6, uninspected) — the server yields control at await server.connect(transport) and never regains a scheduling role SRC-1:270-271
Decision policy and its form none. No configuration branch, no mode selection ABS-1
Context selection and framing none —
State reads and writes constructs the CMP-5 singleton at module scope, before runServer() is called; state is therefore process-global and shared by every request on the connection SRC-1:249
Action executor and boundary stderr readiness line; no other effect SRC-1:272
Persistence none across process restarts (ABS-2) —
Coordination and return single process, one transport, one server instance SRC-1:237-249
Retry / cancellation / recovery none. Any rejection from connect → log to stderr → process.exit(1). No retry, no backoff, no graceful shutdown, no signal handler SRC-1:275-278
Output readiness log; then the process is a passive responder SRC-1:272

Materiality: establishes that all retained state is process-scoped and singleton, which is the precondition for the memory lens's read-back question, and establishes that the server holds no scheduling role at any point.

Loop B — tool advertisement (RTE-2)

Field Record Evidence
Trigger / input host tools/list request SRC-1:251
Next-step owner the host, immediately —
Decision policy and its form none — an unconditional return of one static array literal. The handler ignores its request argument entirely SRC-1:251-253
Context selection and framing the server's only outbound framing act: it hands the host OBJ-1 (54 lines of imperative natural-language instruction) and OBJ-2 (a 9-property JSON Schema). Selection is degenerate — the same descriptor every time, regardless of request, session, or accumulated state SRC-1:133-235
State reads and writes none. OBJ-4/OBJ-5 are not consulted; the descriptor does not vary with history ABS-3
Action executor and boundary response over stdio; boundary ends at the transport —
Persistence the descriptor is compiled into the shipped artifact (RTE-13); it is static shipped material, not accumulated CMP-9
Coordination and return synchronous single return —
Retry / cancellation / recovery none —
Output {tools: [SEQUENTIAL_THINKING_TOOL]} SRC-1:252

Materiality: this is the route carrying BAP-1, the system's only advisory-force authority path toward the model, and it is where every knowledge-production claim (CLM-1–CLM-3, CLM-5, CLM-10) physically resides. It is also the anti-conflation boundary: a tool schema present in context is not tool execution.

Loop C — thought recording (RTE-3–RTE-11) — the primary loop

Field Record Evidence
Trigger / input host tools/call with name and an arguments object authored by the model SRC-1:255-257
Next-step owner the host and model, unconditionally. The server returns and yields. Nothing schedules, requests, or requires a subsequent call. nextThoughtNeeded is copied input→output unchanged and is never branched on (ABS-7) SRC-1:49, 111
Decision policy and its form exactly three, all deterministic, all in imperative TypeScript: (a) name equality request.params.name === "sequentialthinking" (RTE-3); (b) envelope validation — four presence-and-type predicates, throwing Error on failure (RTE-4); (c) branch routing — branchFromThought && branchId both truthy (RTE-7). Nothing else decides anything
Note on (b): !data.thought and !data.thoughtNumber are falsy-checks, so thought: "" and thoughtNumber: 0 are rejected with type-shaped messages. revisesThought, branchFromThought, branchId, needsMoreThoughts are cast, not checked (as assertions at SRC-1:50-54) — a caller can put any type in them and the server will store and render it SRC-1:32-43, 50-54, 96
Context selection and framing no selection. The outbound payload OBJ-6 is a fixed 5-field shape. Framing toward the model is minimal metadata. Framing toward the human is OBJ-8, a chalk-colored unicode box carrying the full thought text — the richest framing in the system, and it goes to stderr, not to any agent SRC-1:58-84, 106-117
State reads and writes writes: OBJ-4.push(validated) on every valid call, unconditional, append-only, never pruned or bounded (RTE-6); OBJ-5[branchId].push(validated) when both branch fields are truthy, with lazy bucket creation (RTE-7) — a branch thought is therefore stored twice, once in each structure, as the same object reference. In-place mutation: RTE-5 writes validatedInput.totalThoughts = thoughtNumber before the push, so the clamped value is what gets stored. reads: exactly two, both at SRC-1:113-114 — Object.keys(OBJ-5) and OBJ-4.length. Content is never read (ABS-3) SRC-1:90-101, 113-114
Action executor and boundary console.error (stderr) and the MCP response. No filesystem, network, or subprocess (ABS-2). The action boundary is the process's own two output streams
Persistence process memory only, for the process lifetime. No serialization, no eviction, no size bound, no TTL. Unbounded growth is possible in a long-lived session; nothing in the boundary addresses it ABS-2
Coordination and return one singleton, no locking, no request identity, no session partitioning. If a host multiplexes several conversations onto one server process, their thoughts interleave in one OBJ-4 with no separator — the code affords this; whether hosts do it is outside the boundary SRC-1:249
Retry / cancellation / recovery validation failure: throw inside try → caught at SRC-1:118 → OBJ-7 returned with isError: true. Crucially the throw happens before SRC-1:94, so a rejected call is not appended — state and history stay clean. unknown tool name: RTE-11, separate error payload, no state touched. no retry, no cancellation handling, no compensating action anywhere SRC-1:88-94, 118-129, 260-266
Output OBJ-6 JSON text block to the host; OBJ-8 box to stderr. thoughtHistoryLength and branches are the only outputs derived from accumulated state SRC-1:106-117

Materiality: this is the loop that determines both lens dispositions.

5.3 Anti-conflation checks

Rule Application here
A filesystem is not a scheduler No filesystem exists (ABS-2); and the in-memory store is likewise not a scheduler — ABS-7 records that nothing in the boundary schedules
Retaining material is not selecting it into context RTE-6/RTE-7 retain full thought records; RTE-9 selects none of that content into any outbound payload. This is the sharpest instance of the rule in this system: retention is total, selection is nil (ABS-3)
A tool schema present in context is not tool execution OBJ-1/OBJ-2 reaching model context via RTE-2/BAP-1 establishes an affordance only. Whether any call follows, and whether the model's behavior changes, is outside the boundary and uninspected

5.4 Conditional surface inventory

Surfaces are inspected only where they materially alter the analysis question, a control path, evidence strength, or a lens result. Materiality is stated for each included surface. This is not a taxonomy, template, ladder, ranking, or adoption advice; surfaces not listed below were judged immaterial and are omitted deliberately.

Surface Included? Materiality statement Finding
Observability yes It is the system's only rich output and the only place thought content leaves the process, so it changes the memory lens's read-back answer and owns BAP-3 RTE-8 writes the full thought, chalk-colored and boxed, to stderr on every valid call, unconditionally and untunably (ABS-1). Content that never returns to the model does reach a human log reader. It is a display path with no consumer inside the boundary
Permissions / governance yes Determines whether any control surface exists for governance to attach to — a null result that bounds several conclusions No permission, auth, rate-limit, quota, or gating mechanism of any kind. The only enforcing surface in the whole boundary is BAP-4, an envelope-shape schema check. Governance has essentially no attachment point here
Packaging / deployment yes RTE-13 determines what artifact actually runs, and the README's recommended npx -y launch makes the deployed revision non-pinned, which bounds every claim tied to 2ecb382 tsc → dist/index.js, files: ["dist"], bin entry. README recommends npx -y @modelcontextprotocol/server-sequential-thinking with no version pin, so an operator following the README runs whatever is latest, not this revision. Combined with the ~20-month boundary age, this prevents any claim that a deployment following the documented configuration runs the analysed code
Providers / model access yes (as a null result) Bears on the scope route in §2 and on ABS-10 The server makes no model call and declares no sampling capability (ABS-10). It is model-adjacent machinery only: the model that gives it meaning runs entirely on the other side of the transport
Performance partial Only the unbounded-growth property is material, because it is a property of the retained store the memory lens analyses OBJ-4 is append-only with no bound, no eviction, no compaction. Per-call cost is O(1) except formatThought's '─'.repeat(...), which is O(len(thought))
User interface no Immaterial — there is none; the stderr render is covered under Observability —
Concurrency / isolation yes Determines whether OBJ-4 is one shared store or many, which changes what the memory lens's read-back finding is about Singleton with no session key or request partitioning (SRC-1:249); see Loop C "coordination and return"