diff --git a/src/config/local-model-catalog.ts b/src/config/local-model-catalog.ts
new file mode 100644
index 00000000..661ebd8b
--- /dev/null
+++ b/src/config/local-model-catalog.ts
@@ -0,0 +1,122 @@
+/**
+ * @fileoverview The local model catalogue: which models, harnesses and chips the recommendation
+ * knows, as a compiled constant validated by a Zod schema.
+ *
+ * SKELETON: the schema below is the shape of the contract (it mirrors `LocalModelCatalog` in
+ * src/types/local-model.ts) and the stock constant is EMPTY. Still to come here:
+ *  - the model rows (ids and byte sizes from the registry manifests, `paramsB`, an empty
+ *    `tested` array each; `flint:40b` stays out), the harness rows and the chips table;
+ *  - the cross-row rules the schema cannot say field by field: unique model ids, unique harness
+ *    `cli`s, `contexts` largest first, `chips` most specific first, `promptCacheTiers` ascending
+ *    and starting at 0;
+ *  - `getLocalModelCatalog()` parsing the constant once, on first use, never at import.
+ *
+ * Rules that hold from the start:
+ *  - There is NO override file and no runtime download data in this stage: nothing here reads
+ *    the data dir, and a data file can never decide what gets recommended.
+ *  - A model id is `name:tag` in lowercase with no slash (`LOCAL_MODEL_ID_PATTERN`), so it can
+ *    only ever name a model of the default registry and namespace.
+ *  - A harness is a ROW (`{ cli, minContext, rank, gated?, slowFirstTurn? }`). The `cli` is a CLI
+ *    registry id as data: no code may compare it with a literal. Whether that CLI exists and can
+ *    take a custom model is checked against the registry at call time, in
+ *    src/local-model/harness-facts.ts, never here.
+ */
+
+import { z } from 'zod';
+import type { LocalModelCatalog } from '../types.js';
+
+/** A model id: lowercase name, one colon, a tag. No slash, so no registry host or namespace can ride along. */
+export const LOCAL_MODEL_ID_PATTERN = /^[a-z0-9][a-z0-9._-]*:[a-z0-9][a-z0-9._-]*$/;
+
+const isoDate = z.string().regex(/^\d{4}-\d{2}-\d{2}$/, 'must be an ISO date (YYYY-MM-DD)');
+const positiveInt = z.number().int().positive();
+
+const TestedOnSchema = z
+  .object({
+    chip: z.string().min(1).max(80),
+    memGb: positiveInt,
+    cli: z.string().min(1).max(24),
+    date: isoDate,
+  })
+  .strict();
+
+const LocalModelEntrySchema = z
+  .object({
+    id: z.string().max(100).regex(LOCAL_MODEL_ID_PATTERN, 'must be name:tag in lowercase, without a slash'),
+    label: z.string().min(1).max(80),
+    license: z.string().min(1).max(40),
+    paramsB: z.number().positive(),
+    bytes: positiveInt,
+    kvBytesPerToken: positiveInt,
+    contexts: z.array(positiveInt).min(1),
+    rank: z.number().int(),
+    speedPer100Gbps: z.number().positive().optional(),
+    tested: z.array(TestedOnSchema),
+  })
+  .strict();
+
+const LocalHarnessEntrySchema = z
+  .object({
+    cli: z.string().min(1).max(24),
+    minContext: positiveInt,
+    rank: z.number().int(),
+    gated: z.boolean().optional(),
+    slowFirstTurn: z.boolean().optional(),
+  })
+  .strict();
+
+const ChipEntrySchema = z
+  .object({
+    match: z.string().min(1).max(40),
+    gbps: z.number().positive(),
+  })
+  .strict();
+
+const PromptCacheTierSchema = z
+  .object({
+    minMemGb: z.number().int().nonnegative(),
+    bytes: z.number().int().nonnegative(),
+  })
+  .strict();
+
+/** Validates a whole catalogue. Typed against `LocalModelCatalog`, so the two cannot drift apart. */
+export const LocalModelCatalogSchema: z.ZodType<LocalModelCatalog> = z
+  .object({
+    schema: z.literal(1),
+    updated: isoDate,
+    minMacosMajor: positiveInt,
+    promptCacheTiers: z.array(PromptCacheTierSchema).min(1),
+    models: z.array(LocalModelEntrySchema),
+    harnesses: z.array(LocalHarnessEntrySchema),
+    chips: z.array(ChipEntrySchema),
+  })
+  .strict();
+
+/**
+ * The catalogue that ships with Codeman. EMPTY for now (no model, harness or chip rows), but
+ * valid: with it `recommend()` can only answer verdict `none`.
+ *
+ * The two constants that are already decided are filled in: macOS 14 is the oldest version the
+ * runtime supports, and the prompt cache is 512 MiB on a Mac below 32 GB and 2 GiB from 32 GB.
+ */
+export const STOCK_LOCAL_MODEL_CATALOG: LocalModelCatalog = {
+  schema: 1,
+  updated: '2026-11-06',
+  minMacosMajor: 14,
+  promptCacheTiers: [
+    { minMemGb: 0, bytes: 512 * 1024 ** 2 },
+    { minMemGb: 32, bytes: 2 * 1024 ** 3 },
+  ],
+  models: [],
+  harnesses: [],
+  chips: [],
+};
+
+/**
+ * The catalogue in force. There is no override in this stage, so this is the stock constant;
+ * callers go through this function anyway, so a later stage can change where it comes from
+ * without touching them.
+ */
+export function getLocalModelCatalog(): LocalModelCatalog {
+  return STOCK_LOCAL_MODEL_CATALOG;
+}
diff --git a/src/local-model/format.ts b/src/local-model/format.ts
new file mode 100644
index 00000000..cc9aa974
--- /dev/null
+++ b/src/local-model/format.ts
@@ -0,0 +1,42 @@
+/**
+ * @fileoverview The formatters of the local model recommendation, and its byte units.
+ *
+ * `formatGb()` is the ONE place a byte count becomes a size a person reads: decimal GB (the
+ * unit the Finder and the model registry use). `hardware.ts` and `recommend.ts` call it to fill
+ * the `...Gb` text fields of the payload (`memGb`, `freeDiskGb`, `needGb`, `downloadGb`,
+ * `budgetGb`, and the size slots of a `LocalModelMessage`). Nothing else may turn bytes into a
+ * size for display, the browser included: it prints the text it was sent.
+ *
+ * GiB and MiB exist only for the budget math (reserves, the wired limit, the prompt cache) and
+ * never reach a person.
+ *
+ * Pure: no IO, no state.
+ */
+
+/** One decimal gigabyte, the unit a person reads. */
+export const GB = 1_000_000_000;
+/** One binary gigabyte. Budget math only. */
+export const GIB = 1024 ** 3;
+/** One binary megabyte. Budget math only. */
+export const MIB = 1024 ** 2;
+
+/**
+ * A byte count as decimal GB text, WITHOUT the unit: one decimal below 100 ('6.6', '17.7',
+ * '25.5'), a whole number from 100 ('212'). The caller's sentence supplies ' GB'.
+ * Anything that is not a positive finite number reads '0.0'.
+ */
+export function formatGb(bytes: number): string {
+  if (!Number.isFinite(bytes) || bytes <= 0) return '0.0';
+  const tenths = Math.round((bytes / GB) * 10) / 10;
+  return tenths >= 100 ? String(Math.round(bytes / GB)) : tenths.toFixed(1);
+}
+
+/**
+ * The memory size a Mac is sold as: whole binary gigabytes (17179869184 bytes is 16). This is
+ * `HardwareFacts.memClassGb`: the key of the tier rules ("below 36 GB") and of `TestedOn.memGb`.
+ * It names a class of Mac. A size for display is `formatGb()`.
+ */
+export function memClassGb(memBytes: number): number {
+  if (!Number.isFinite(memBytes) || memBytes <= 0) return 0;
+  return Math.round(memBytes / GIB);
+}
diff --git a/src/local-model/hardware.ts b/src/local-model/hardware.ts
new file mode 100644
index 00000000..687d981a
--- /dev/null
+++ b/src/local-model/hardware.ts
@@ -0,0 +1,106 @@
+/**
+ * @fileoverview The hardware probe of the local model recommendation: what this Mac is.
+ *
+ * SKELETON: the exported signatures are final, the bodies are not written yet. This module
+ * will hold:
+ *  - `parseSysctl()`: a pure parser of `key: value` lines. The command runs WITHOUT `-n`, so a
+ *    key that is missing on a machine (`sysctl.proc_translated` on Intel) cannot shift the
+ *    others, and a line it does not know is ignored.
+ *  - `readHardware()`: ONE bounded async spawn of `SYSCTL_PATH` with `SYSCTL_KEYS`, the free disk
+ *    of the data dir through `fs.promises.statfs`, fallbacks from `node:os` when the spawn
+ *    fails, and a 60 s cache.
+ *
+ * Rules:
+ *  - Never throws and never rejects: a failed probe is an answer (`source: 'os-fallback'`), and
+ *    off macOS nothing is spawned (`source: 'not-probed'`).
+ *  - Never `system_profiler` (tens of milliseconds and a parse of free text), never a second
+ *    spawn, never a synchronous exec on the server's event loop.
+ *  - A non-zero exit is tolerated once `hw.memsize` parsed (a missing key makes sysctl exit 1).
+ *  - `iogpu.wired_limit_mb` of 0 means "not set": it is reported as 0 and only a value above 0
+ *    is ever used as a limit.
+ *  - `memGb`, `memClassGb` and `freeDiskGb` are filled here through src/local-model/format.ts,
+ *    the one place a size is formatted.
+ */
+
+import type { HardwareFacts } from '../types.js';
+
+/** Absolute path, so the server's PATH (minimal under a service manager) cannot change what runs. */
+export const SYSCTL_PATH = '/usr/sbin/sysctl';
+
+/** The keys of the one spawn, in the order they are passed. */
+export const SYSCTL_KEYS = [
+  'hw.memsize',
+  'machdep.cpu.brand_string',
+  'hw.optional.arm64',
+  'sysctl.proc_translated',
+  'iogpu.wired_limit_mb',
+  'kern.osproductversion',
+  'hw.model',
+] as const;
+
+/** Upper bound of the spawn (it answers in about 2 ms on a real Mac). */
+export const SYSCTL_TIMEOUT_MS = 2000;
+
+/** How long one probe result is reused. */
+export const HARDWARE_CACHE_TTL_MS = 60_000;
+
+/** What `parseSysctl()` read. Every field is absent when its key was missing or its value did not parse. */
+export interface SysctlFacts {
+  /** `hw.memsize`. */
+  memBytes?: number;
+  /** `machdep.cpu.brand_string`. */
+  chip?: string;
+  /** `hw.optional.arm64` is 1. */
+  arm64?: boolean;
+  /** `sysctl.proc_translated` is 1. */
+  translated?: boolean;
+  /** `iogpu.wired_limit_mb`, as reported (0 stays 0). */
+  wiredLimitMb?: number;
+  /** `kern.osproductversion`. */
+  macosVersion?: string;
+  /** The leading number of `macosVersion`. */
+  macosMajor?: number;
+  /** `hw.model`. */
+  model?: string;
+}
+
+/** The IO of `readHardware()`, injectable so a test spawns nothing and reads no real disk. Each member defaults to the real thing. */
+export interface HardwareProbeDeps {
+  /** Default `process.platform`. */
+  platform?: string;
+  /** Default `os.arch()`. */
+  arch?: string;
+  /** Runs the one spawn. Resolves its stdout, also after a non-zero exit, or `undefined` when it could not run or timed out. Never rejects. */
+  runSysctl?: () => Promise<string | undefined>;
+  /** Free bytes on the data dir's filesystem, or `undefined` when unknown. Never rejects. */
+  freeDiskBytes?: () => Promise<number | undefined>;
+  /** Default `os.totalmem()`. */
+  totalMemBytes?: () => number;
+  /** Default `os.cpus()[0]?.model`. */
+  cpuModel?: () => string | undefined;
+  /** Default `Date.now`. The clock of the cache. */
+  now?: () => number;
+}
+
+/**
+ * Parse the output of `sysctl <keys>` (no `-n`): one `key: value` line per key it knows.
+ * Pure. Unknown lines, blank lines and error lines are skipped.
+ */
+export function parseSysctl(text: string): SysctlFacts {
+  void text;
+  throw new Error('not implemented: parseSysctl');
+}
+
+/**
+ * What this machine is. Cached for `HARDWARE_CACHE_TTL_MS`; concurrent callers share one probe.
+ * Never rejects.
+ */
+export async function readHardware(deps?: HardwareProbeDeps): Promise<HardwareFacts> {
+  void deps;
+  throw new Error('not implemented: readHardware');
+}
+
+/** Drop the cached probe result (tests, and nothing else). */
+export function resetHardwareCache(): void {
+  throw new Error('not implemented: resetHardwareCache');
+}
diff --git a/src/local-model/harness-facts.ts b/src/local-model/harness-facts.ts
new file mode 100644
index 00000000..7a27d130
--- /dev/null
+++ b/src/local-model/harness-facts.ts
@@ -0,0 +1,30 @@
+/**
+ * @fileoverview What the server knows about each catalogue harness on this machine, for the
+ * local model recommendation. Server side: this is the one module of src/local-model/ that
+ * reads the CLI registry, so `recommend()` can stay pure and name no CLI.
+ *
+ * SKELETON: the exported signature is final, the body is not written yet. `buildHarnessFacts()`
+ * will, for every `LocalHarnessEntry` of the catalogue:
+ *  - resolve its `cli` in the CLI registry AT CALL TIME (never in a module-level constant), and
+ *    leave out a row whose CLI is unknown, disabled, or has no custom model mechanism
+ *    (`capabilities.customModelInjection.kind` is `unsupported`);
+ *  - report `label` from the registry entry and `installed` from the same probe the other
+ *    routes use;
+ *  - report `installable` only for a CLI that is not installed and whose install command for
+ *    this platform needs no administrator rights (not one that starts with `brew` or `sudo`);
+ *  - supply `acceptsModelId`, the same test a custom model launch applies to the model id
+ *    before anything is written (the launch spec's model pattern).
+ *
+ * Rules:
+ *  - No CLI id is compared with a literal here or anywhere: the id comes from the catalogue row
+ *    and everything else from the registry entry it resolves to.
+ *  - Read-only: nothing is installed, written or spawned beyond the existing availability probe.
+ */
+
+import type { HarnessFact, LocalModelCatalog } from '../types.js';
+
+/** One fact per catalogue harness that resolves in the CLI registry, in catalogue order. */
+export async function buildHarnessFacts(catalog: LocalModelCatalog): Promise<HarnessFact[]> {
+  void catalog;
+  throw new Error('not implemented: buildHarnessFacts');
+}
diff --git a/src/local-model/recommend.ts b/src/local-model/recommend.ts
new file mode 100644
index 00000000..2536e63c
--- /dev/null
+++ b/src/local-model/recommend.ts
@@ -0,0 +1,68 @@
+/**
+ * @fileoverview The recommendation itself: which model, at which context, with which harness
+ * fits this Mac. Pure: no IO, no clock, no CLI registry, no data dir.
+ *
+ * SKELETON: the exported signatures are final, the bodies are not written yet. This module
+ * will hold:
+ *  - `deviceBudget()`: L is the wired limit when it is above 0, else 2/3 of memory below 36 GB
+ *    and 3/4 from 36 GB. B = min(L - 1 GiB, memory - reserve), with a reserve of 6 GiB up to
+ *    18 GB, 8 GiB up to 48 GB and 12 GiB from 64 GB.
+ *  - `needBytes()`: F = weights + kvBytesPerToken * ctx + 1 GiB + the prompt cache tier of the
+ *    catalogue for this Mac's memory.
+ *  - `recommend()`: the candidates (model, context, harness) with `ctx >= harness.minContext`,
+ *    the harness installed or installable, accepting the model id and not gated; the fit (F/B up
+ *    to 0.85 good, up to 0.98 tight, above out); the speed (ok, slow or unknown: a chip that is
+ *    in no chips row is unknown, a bandwidth is never guessed); the ranking (good before tight,
+ *    then ok before unknown before slow, then model rank, harness rank, larger context); and the
+ *    verdict.
+ *
+ * Rules:
+ *  - Verdict `limited` when the best candidate's model has fewer than 12 billion parameters.
+ *  - The word "Recommended" (`LOCAL_MODEL_LABELS.headlineTested`) only for a pick whose model
+ *    has a `tested` entry matching this Mac. Otherwise `headlineOk` plus `noteUntested`.
+ *  - Reasons for `none`: not-macos, intel, memory, disk (free disk minus the download is below
+ *    10 GiB for every fitting model), macos, no-harness.
+ *  - Every label in the result comes from `LOCAL_MODEL_LABELS`, every size text from
+ *    `formatGb()`. No number is spliced into a sentence here.
+ *  - No CLI id is ever compared with a literal: a harness is a catalogue row plus a
+ *    `HarnessFact`.
+ */
+
+import type {
+  DeviceBudget,
+  HardwareFacts,
+  HarnessFact,
+  LocalModelCatalog,
+  LocalModelEntry,
+  Recommendation,
+} from '../types.js';
+
+/** The memory a model may use on this Mac: the device limit L, the budget B and where L came from. */
+export function deviceBudget(hw: HardwareFacts): DeviceBudget {
+  void hw;
+  throw new Error('not implemented: deviceBudget');
+}
+
+/** F: the bytes `model` needs in memory at a context of `ctx` tokens on this Mac. */
+export function needBytes(model: LocalModelEntry, ctx: number, catalog: LocalModelCatalog, hw: HardwareFacts): number {
+  void model;
+  void ctx;
+  void catalog;
+  void hw;
+  throw new Error('not implemented: needBytes');
+}
+
+/**
+ * The recommendation for this Mac. `harnessFacts` holds one fact per catalogue harness the
+ * caller could resolve; a catalogue harness without a fact is not offered.
+ */
+export function recommend(
+  hw: HardwareFacts,
+  catalog: LocalModelCatalog,
+  harnessFacts: readonly HarnessFact[]
+): Recommendation {
+  void hw;
+  void catalog;
+  void harnessFacts;
+  throw new Error('not implemented: recommend');
+}
diff --git a/src/types/index.ts b/src/types/index.ts
index 4b74da44..592b28e2 100644
--- a/src/types/index.ts
+++ b/src/types/index.ts
@@ -29,6 +29,7 @@
  * | plan         | PlanItem, PlanTaskStatus, TddPhase                                    | In-memory → `GET /api/sessions/:id/plan/tasks` |
  * | orchestrator | OrchestratorState, OrchestratorPlan, OrchestratorConfig, OrchestratorPersistState | `~/.codeman/state.json` → `GET /api/orchestrator/status` |
  * | mcp-sync     | McpSyncResult, McpSyncTargetResult                                    | Other CLIs' own config files → `GET`/`POST /api/mcp-sync` |
+ * | local-model  | HardwareFacts, LocalModelCatalog, Candidate, Recommendation, LocalModelStatus, LOCAL_MODEL_LABELS | In-memory only (nothing persisted) → `GET /api/local-model` |
  *
  * ## Cross-domain relationship map
  *
@@ -77,3 +78,4 @@ export * from './webview.js';
 export * from './intent.js';
 export * from './foreign-tmux.js';
 export * from './mcp-sync.js';
+export * from './local-model.js';
diff --git a/src/types/local-model.ts b/src/types/local-model.ts
new file mode 100644
index 00000000..5298c3bb
--- /dev/null
+++ b/src/types/local-model.ts
@@ -0,0 +1,357 @@
+/**
+ * @fileoverview Types of the hardware-aware local model recommendation: what the server sees of
+ * this Mac, the catalogue of models and harnesses, and the answer of `GET /api/local-model`.
+ *
+ * This stage is read-only: Codeman looks at the Mac and recommends. It downloads nothing,
+ * installs nothing and writes no file.
+ *
+ * Who produces what:
+ *  - `HardwareFacts`: src/local-model/hardware.ts (one bounded `sysctl` spawn, never throws).
+ *  - `LocalModelCatalog` and its rows: src/config/local-model-catalog.ts (a compiled constant).
+ *  - `HarnessFact`: src/local-model/harness-facts.ts (server only, read from the CLI registry at
+ *    call time; it holds a function, so it never goes over HTTP).
+ *  - `Recommendation`, `Candidate`, `DeviceBudget`: src/local-model/recommend.ts (pure).
+ *  - `LocalModelStatus`: src/web/routes/local-model-routes.ts (the `data` of the GET).
+ *
+ * Three rules every producer and consumer follows:
+ *
+ * 1. ONE unit for a size a person reads: decimal GB, computed from bytes by `formatGb()` in
+ *    src/local-model/format.ts. Every such size travels twice, as bytes (`needBytes`) and as the
+ *    text to show (`needGb`, a number without the unit, such as '25.5'). The browser prints the
+ *    text and never divides bytes itself. GiB appears only inside the budget math.
+ * 2. Every sentence or label the SERVER chooses comes from `LOCAL_MODEL_LABELS` below, so the
+ *    browser can translate it (`codemanT(text, vars)`) and its i18n test can list every string.
+ *    Numbers are never spliced into a sentence here: they travel in `vars` and fill the
+ *    `{placeholder}` slots.
+ * 3. A CLI id is DATA (`LocalHarnessEntry.cli`, `Candidate.cli`). No code compares one with a
+ *    literal: what differs between harnesses is a catalogue field or a `HarnessFact`.
+ */
+
+// ---------- Hardware ----------
+
+/**
+ * How `HardwareFacts` was obtained.
+ *  - `sysctl`: the spawn answered and `hw.memsize` parsed.
+ *  - `os-fallback`: on macOS, but the spawn failed or timed out; memory, architecture and the chip
+ *    string come from `node:os`, the rest is absent.
+ *  - `not-probed`: not macOS, so `sysctl` was never spawned.
+ */
+export type HardwareProbeSource = 'sysctl' | 'os-fallback' | 'not-probed';
+
+/**
+ * What the server knows about the machine it runs on. Plain JSON (it is part of the GET payload),
+ * and always an answer: a failed probe yields the `os-fallback` or `not-probed` shape, never an
+ * exception.
+ */
+export interface HardwareFacts {
+  /** `process.platform` of the server. Anything but `darwin` ends in verdict `none`, reason `not-macos`. */
+  platform: string;
+  /** `os.arch()` of the server process. `x64` on Apple silicon means Node runs under Rosetta. */
+  arch: string;
+  /** `hw.optional.arm64` is 1: the MACHINE is Apple silicon whatever `arch` says. Absent when the key was not read. */
+  arm64?: boolean;
+  /** `sysctl.proc_translated` is 1: this process runs under Rosetta. Absent when the key was not read (Intel Macs lack it). */
+  translated?: boolean;
+  /** Installed memory in bytes (`hw.memsize`, else `os.totalmem()`). The ONLY memory input of the budget math. */
+  memBytes: number;
+  /** `memBytes` as a person reads it: decimal GB from `formatGb()`, without the unit ('17.2' for a Mac sold as 16 GB). */
+  memGb: string;
+  /** The memory size the Mac is sold as: whole binary gigabytes (16, 32, 48). Tier rules and `TestedOn.memGb` use it. */
+  memClassGb: number;
+  /** `machdep.cpu.brand_string` ('Apple M4 Pro'), else `os.cpus()[0].model`. */
+  chip?: string;
+  /** `hw.model` ('Mac16,10'). */
+  model?: string;
+  /** `kern.osproductversion` ('27.2'). */
+  macosVersion?: string;
+  /** The leading number of `macosVersion` (27). */
+  macosMajor?: number;
+  /** `iogpu.wired_limit_mb` exactly as reported. 0 means "not set" (both test Macs report 0); only a value above 0 is a limit. */
+  wiredLimitMb?: number;
+  /** Free bytes on the filesystem of Codeman's data dir (`statfs`: `bavail * bsize`). */
+  freeDiskBytes?: number;
+  /** `freeDiskBytes` as a person reads it (decimal GB, no unit). Present exactly when `freeDiskBytes` is. */
+  freeDiskGb?: string;
+  source: HardwareProbeSource;
+}
+
+// ---------- Catalogue ----------
+
+/** One Mac a model and harness pair was really run on by us. A model row with a matching entry may be called "Recommended". */
+export interface TestedOn {
+  /** The chip, as `machdep.cpu.brand_string` reports it ('Apple M4'). */
+  chip: string;
+  /** The Mac's memory as it is sold (`HardwareFacts.memClassGb`: 16, 32, 48). */
+  memGb: number;
+  /** The harness it was tested with: a CLI registry id, as data. */
+  cli: string;
+  /** ISO date of the test ('2026-11-06'). */
+  date: string;
+}
+
+/** One model of the catalogue. */
+export interface LocalModelEntry {
+  /** `name:tag` exactly as the model registry lists it. Lowercase, one colon, no slash (`LOCAL_MODEL_ID_PATTERN`). */
+  id: string;
+  /** The name a person reads ('Qwen3.8 27B'). */
+  label: string;
+  /** SPDX id of the license ('Apache-2.0'). */
+  license: string;
+  /** Parameter count in billions. Under 12 the verdict is `limited`, never `ok`. */
+  paramsB: number;
+  /** Size of the weights in bytes: both the download and what they take in memory. */
+  bytes: number;
+  /** Bytes of KV cache one token of context costs. */
+  kvBytesPerToken: number;
+  /** Context lengths (tokens) the model may be run at, largest first. */
+  contexts: number[];
+  /** Preference among models that fit: the HIGHER rank wins. A judgement, not a measurement. */
+  rank: number;
+  /** Measured tokens per second per 100 GB/s of memory bandwidth. Absent: the speed of this model is unknown. */
+  speedPer100Gbps?: number;
+  /** Macs this model was really run on. Empty today for every row. */
+  tested: TestedOn[];
+}
+
+/** One harness (coding agent CLI) that can be connected to a local model. All of it is data. */
+export interface LocalHarnessEntry {
+  /** A CLI registry id. Data only: never compared with a literal anywhere. */
+  cli: string;
+  /** The smallest context (tokens) at which this harness works. */
+  minContext: number;
+  /** Preference among harnesses: the HIGHER rank wins. */
+  rank: number;
+  /** True: listed in the catalogue but never offered yet (its use with a local model is unverified). */
+  gated?: boolean;
+  /** True: the first answer takes minutes, because the harness sends a very large fixed prompt. */
+  slowFirstTurn?: boolean;
+}
+
+/**
+ * Memory bandwidth of one chip family. `LocalModelCatalog.chips` is ordered most specific first
+ * ('M4 Max' before 'M4') and the first row whose `match` occurs in `HardwareFacts.chip` wins. A
+ * chip that matches no row has an UNKNOWN speed: a bandwidth is never guessed.
+ */
+export interface ChipEntry {
+  /** Text that must occur in the chip string ('M4 Max'). */
+  match: string;
+  /** Memory bandwidth in GB/s. */
+  gbps: number;
+}
+
+/**
+ * Host memory the runtime's prompt cache takes, by the size of the Mac. Tiers are ordered by
+ * `minMemGb` ascending and the last tier with `minMemGb <= HardwareFacts.memClassGb` applies.
+ */
+export interface PromptCacheTier {
+  /** Smallest memory size (as sold, binary gigabytes) this tier applies to. The first tier has 0. */
+  minMemGb: number;
+  bytes: number;
+}
+
+/** The catalogue: a compiled constant, validated by `LocalModelCatalogSchema`. No override file, no download data. */
+export interface LocalModelCatalog {
+  schema: 1;
+  /** ISO date the rows were last checked ('2026-11-06'). Reported as `LocalModelStatus.catalogUpdated`. */
+  updated: string;
+  /** Oldest macOS major version a local model runs on. Below it: verdict `none`, reason `macos`. */
+  minMacosMajor: number;
+  promptCacheTiers: PromptCacheTier[];
+  models: LocalModelEntry[];
+  harnesses: LocalHarnessEntry[];
+  chips: ChipEntry[];
+}
+
+// ---------- Harness facts (server only) ----------
+
+/**
+ * What the server knows about one catalogue harness on this machine. Built from the CLI registry
+ * at call time, so `recommend()` names no CLI. NOT serializable (it holds a function): it never
+ * leaves the server. `Candidate` carries the parts a browser needs.
+ */
+export interface HarnessFact {
+  /** The CLI registry id. */
+  cli: string;
+  /** The registry's display label ('OpenCode'). */
+  label: string;
+  /** The CLI's binary was found on this machine. */
+  installed: boolean;
+  /** Not installed, but the registry has an install command for this platform that needs no administrator rights. */
+  installable: boolean;
+  /** Whether this CLI can be launched with that model id (its command-line pattern accepts it). */
+  acceptsModelId: (modelId: string) => boolean;
+}
+
+// ---------- Recommendation ----------
+
+/** Need over budget: up to 0.85 is `good`, up to 0.98 is `tight`, above is `out`. */
+export type FitGrade = 'good' | 'tight' | 'out';
+
+/**
+ * Expected generation speed. `unknown` when the chip is in no `ChipEntry` or the model has no
+ * `speedPer100Gbps`. In the ranking `unknown` sits between `ok` and `slow`.
+ */
+export type SpeedGrade = 'ok' | 'slow' | 'unknown';
+
+/**
+ * Why the verdict is `none`.
+ *  - `not-macos`: the server does not run on macOS (the card is hidden).
+ *  - `intel`: a Mac without Apple silicon.
+ *  - `memory`: no model fits the memory budget with any harness.
+ *  - `disk`: models fit the memory, but for every one of them free disk minus the download is below 10 GiB.
+ *  - `macos`: macOS is older than `LocalModelCatalog.minMacosMajor`.
+ *  - `no-harness`: no catalogue harness is installed or installable and accepts a model.
+ */
+export type NoneReason = 'not-macos' | 'intel' | 'memory' | 'disk' | 'macos' | 'no-harness';
+
+/** Where the device budget came from: a formula (`estimated`) or `iogpu.wired_limit_mb` above 0 (`wired-limit`). */
+export type BudgetSource = 'estimated' | 'wired-limit';
+
+/** The memory a model may use on this Mac. */
+export interface DeviceBudget {
+  /** L: the wired limit when above 0, else 2/3 of memory below 36 GB and 3/4 from 36 GB. */
+  limitBytes: number;
+  /** B = min(L - 1 GiB, memory - reserve). What `Candidate.budgetShare` is measured against. */
+  budgetBytes: number;
+  source: BudgetSource;
+}
+
+/**
+ * Every sentence and label the server may put into the payload, in English (the i18n source
+ * language). Frozen for the parallel build: the zh-CN dictionary in src/web/public/i18n.js has
+ * one entry per value, keyed by this exact text, and the browser's i18n test imports this
+ * constant to list them. Adding a key is fine; changing a text means changing its zh-CN key too.
+ *
+ * `{placeholder}` slots are filled by the browser from `LocalModelMessage.vars`. `{name}` is
+ * taken (the translator fills it with the display name), so no slot here is called `name`.
+ *
+ * | Key           | Slots (all text; sizes are decimal GB without the unit)                         |
+ * |---------------|---------------------------------------------------------------------------------|
+ * | `noneMemory`  | `memory`: `HardwareFacts.memGb`                                                 |
+ * | `noneDisk`    | `download`: smallest download among the models that fit the memory; `free`:     |
+ * |               | `HardwareFacts.freeDiskGb`; `missing`: download + 10 GiB - free                 |
+ * | `noneMacos`   | `version`: `HardwareFacts.macosVersion`; `minimum`: the catalogue's minimum     |
+ *
+ * The word "Recommended" exists only in `headlineTested`, which may be used only when the
+ * pick's `tested` is true. No catalogue row has a tested entry today, so it is never sent.
+ */
+export const LOCAL_MODEL_LABELS = {
+  /** Verdict `ok`, pick not tested by us on a Mac like this one. */
+  headlineOk: 'Best fit for this Mac',
+  /** Verdict `ok`, pick tested by us on a Mac like this one. */
+  headlineTested: 'Recommended for this Mac',
+  /** Verdict `limited`. */
+  headlineLimited:
+    'This Mac can run a small model. It handles small edits and questions. It does not replace a cloud model.',
+  /** A note under an `ok` or `limited` pick whose `tested` is false. */
+  noteUntested: 'Not yet tested by us on a Mac like this.',
+  fitGood: 'Good',
+  fitTight: 'Tight',
+  speedSlow: 'Slow',
+  speedUnknown: 'Speed unknown',
+  noneNotMacos: 'Codeman recommends a local model only on a Mac with Apple silicon.',
+  noneIntel: 'This Mac has an Intel processor. Local coding models need Apple silicon.',
+  noneMemory:
+    'This Mac has {memory} GB of memory. That is too little to run a model that can drive a coding agent, so Codeman recommends none here.',
+  noneDisk:
+    'Not enough free disk space. The smallest model that fits this Mac is a {download} GB download and {free} GB is free. Free up about {missing} GB.',
+  noneMacos: 'This Mac runs macOS {version}. Local models need macOS {minimum} or newer.',
+  noneNoHarness: 'No coding agent that Codeman can connect to a local model is available on this Mac.',
+} as const;
+
+/** One of the texts in `LOCAL_MODEL_LABELS`. The payload's label fields are typed with it, so an off-list string does not compile. */
+export type LocalModelLabel = (typeof LOCAL_MODEL_LABELS)[keyof typeof LOCAL_MODEL_LABELS];
+
+/** The headline of each `none` reason. */
+export const LOCAL_MODEL_NONE_LABELS: Record<NoneReason, LocalModelLabel> = {
+  'not-macos': LOCAL_MODEL_LABELS.noneNotMacos,
+  intel: LOCAL_MODEL_LABELS.noneIntel,
+  memory: LOCAL_MODEL_LABELS.noneMemory,
+  disk: LOCAL_MODEL_LABELS.noneDisk,
+  macos: LOCAL_MODEL_LABELS.noneMacos,
+  'no-harness': LOCAL_MODEL_LABELS.noneNoHarness,
+};
+
+/** A sentence for the card: a text from `LOCAL_MODEL_LABELS` plus the values of its `{placeholder}` slots. */
+export interface LocalModelMessage {
+  text: LocalModelLabel;
+  /** Slot values, already formatted as text. Absent when the text has no slot. */
+  vars?: Record<string, string>;
+}
+
+/** One model at one context with one harness, measured against this Mac. Plain JSON. */
+export interface Candidate {
+  /** `LocalModelEntry.id`. */
+  modelId: string;
+  /** `LocalModelEntry.label`. */
+  modelLabel: string;
+  license: string;
+  paramsB: number;
+  /** Context length in tokens. */
+  context: number;
+  /** The harness: a CLI registry id, as data. */
+  cli: string;
+  /** The harness's display label, from the CLI registry. */
+  cliLabel: string;
+  /** False: the harness is not on this machine yet (it is installable, or it would not be a candidate). */
+  cliInstalled: boolean;
+  /** The harness row's `slowFirstTurn`. */
+  slowFirstTurn?: boolean;
+  /** F = weights + kvBytesPerToken * context + 1 GiB + prompt cache. */
+  needBytes: number;
+  /** `needBytes` as decimal GB text, no unit. */
+  needGb: string;
+  /** The model download in bytes (`LocalModelEntry.bytes`). */
+  downloadBytes: number;
+  /** `downloadBytes` as decimal GB text, no unit. */
+  downloadGb: string;
+  /** `needBytes / Recommendation.budgetBytes` (0.83). */
+  budgetShare: number;
+  /** A candidate in a `Recommendation` is never `out`. */
+  fit: Exclude<FitGrade, 'out'>;
+  /** `fitGood` or `fitTight`. */
+  fitLabel: LocalModelLabel;
+  speed: SpeedGrade;
+  /** `speedSlow` or `speedUnknown`. Absent when `speed` is `ok`. */
+  speedLabel?: LocalModelLabel;
+  /** Estimated generation speed. Present exactly when `speed` is not `unknown`. */
+  tokensPerSecond?: number;
+  /** A `TestedOn` entry of the model matches this Mac (same chip, same `memClassGb`) and this harness. */
+  tested: boolean;
+}
+
+/**
+ * The answer of `recommend()`.
+ *  - `ok`: `pick` is the best candidate and its model has at least 12 billion parameters.
+ *  - `limited`: `pick` is the best candidate, but its model has fewer than 12 billion parameters.
+ *    The card says so and never says "Recommended".
+ *  - `none`: no pick; `reason` says why.
+ */
+export interface Recommendation {
+  verdict: 'ok' | 'limited' | 'none';
+  /** Present exactly when `verdict` is `none`. */
+  reason?: NoneReason;
+  /** What the card says first: `headlineOk`, `headlineTested`, `headlineLimited` or the `none` reason's sentence. */
+  headline: LocalModelMessage;
+  /** Further sentences under the headline (`noteUntested` today). May be empty. */
+  notes: LocalModelMessage[];
+  /** Present exactly when `verdict` is `ok` or `limited`. */
+  pick?: Candidate;
+  /** The next models that fit (at most four, each at its best context and harness), best first. Empty when `verdict` is `none`. */
+  alternatives: Candidate[];
+  /** `DeviceBudget.budgetBytes`. 0 when the budget could not be computed (not macOS). */
+  budgetBytes: number;
+  /** `budgetBytes` as decimal GB text, no unit. */
+  budgetGb: string;
+  budgetSource: BudgetSource;
+}
+
+// ---------- API ----------
+
+/** The `data` of `GET /api/local-model`. Read-only; admin only in multi-user mode. */
+export interface LocalModelStatus {
+  hardware: HardwareFacts;
+  recommendation: Recommendation;
+  /** `LocalModelCatalog.updated`. */
+  catalogUpdated: string;
+}
diff --git a/src/web/public/index.html b/src/web/public/index.html
index c55ad232..d7b82775 100644
--- a/src/web/public/index.html
+++ b/src/web/public/index.html
@@ -4685,6 +4685,7 @@
   <script defer src="foreign-sessions.js"></script>
   <script defer src="git-status-ui.js"></script>
   <script defer src="edit-history-ui.js"></script>
+  <script defer src="local-model-ui.js"></script>
   <script defer src="entrance-animations.js"></script>
   <script defer src="ralph-wizard.js"></script>
   <script defer src="api-client.js"></script>
diff --git a/src/web/public/local-model-ui.js b/src/web/public/local-model-ui.js
new file mode 100644
index 00000000..755527bf
--- /dev/null
+++ b/src/web/public/local-model-ui.js
@@ -0,0 +1,33 @@
+/**
+ * @fileoverview The "model on this Mac" card of the welcome screen and its row in App Settings.
+ *
+ * SKELETON: this file holds no code yet. It will read `GET /api/local-model` (hardware of the
+ * machine the server runs on, the recommendation, the catalogue date) and show, read-only:
+ *  - the hardware line (chip, memory, free disk);
+ *  - the verdict: the headline and notes the server sent, then the pick with its numbers
+ *    (model, harness, context, memory need against the budget, download size, speed);
+ *  - the other models that fit, each with its fit and speed label;
+ *  - one line saying that setting the model up from Codeman is the next step and is not built
+ *    yet.
+ *
+ * Rules:
+ *  - Read-only: no button here downloads, installs or writes anything.
+ *  - Hidden when the server is not on macOS (`recommendation.reason` is `not-macos`), when the
+ *    request is refused (a non-admin in multi-user mode gets a 403) and after the user dismissed
+ *    the card on this device (a localStorage key, never a server setting).
+ *  - Every dynamic string goes in through `textContent`. Model, harness and chip names are
+ *    someone else's text and carry `data-i18n-skip`.
+ *  - Names and labels come from the payload: this file holds no list of models or harnesses and
+ *    never compares a CLI id with a literal.
+ *  - Sizes are printed exactly as sent (`needGb`, `downloadGb`, `budgetGb`, `memGb`,
+ *    `freeDiskGb`: decimal GB as text). Bytes are never divided here.
+ *  - A sentence the server chose arrives as `{ text, vars }` and goes through
+ *    `codemanT(text, vars)`; this file's own strings are literals in its translator call, so the
+ *    i18n test can harvest them. Both kinds need a zh-CN entry in i18n.js.
+ *
+ * @mixin Extends CodemanApp.prototype via Object.assign
+ * @dependency app.js (CodemanApp)
+ * @dependency api-client.js (_api)
+ * @dependency i18n.js (codemanT, optional)
+ * @loadorder 12.59 of 16, after edit-history-ui.js, before entrance-animations.js
+ */
diff --git a/src/web/routes/index.ts b/src/web/routes/index.ts
index 2dde7fa3..31db304e 100644
--- a/src/web/routes/index.ts
+++ b/src/web/routes/index.ts
@@ -49,5 +49,6 @@ export {
   type CustomModelSwapDisplacement,
 } from './custom-model-routes.js';
 export { registerCliRegistryRoutes, readCliManagementEnabled, type CliListItem } from './cli-registry-routes.js';
+export { registerLocalModelRoutes } from './local-model-routes.js';
 
 export { registerAgentSessionRoutes } from './agent-session-routes.js';
diff --git a/src/web/routes/local-model-routes.ts b/src/web/routes/local-model-routes.ts
new file mode 100644
index 00000000..4c4f7563
--- /dev/null
+++ b/src/web/routes/local-model-routes.ts
@@ -0,0 +1,60 @@
+/**
+ * @fileoverview `GET /api/local-model`: what this Mac is and which local model fits it.
+ *
+ * SKELETON: the route is registered and answers 501 until its handler is written. It will
+ * answer `{ success: true, data: LocalModelStatus }`, built from the hardware probe, the
+ * catalogue, the harness facts and the pure `recommend()`:
+ * `{ hardware, recommendation, catalogUpdated }`.
+ *
+ * Rules:
+ *  - Read-only. It downloads nothing, installs nothing, writes no file and reads no setting.
+ *  - Never a 500 for a probe that failed: a failed probe is an answer (the hardware's `source`
+ *    says so and the recommendation is verdict `none`).
+ *  - The payload names hardware of the host, so in multi-user mode it is admin only (403), the
+ *    same bar as `GET /api/doctor`.
+ *  - Every dependency is injected (`LocalModelRouteDeps`), so a route test spawns nothing and
+ *    does not need a Mac: it passes its own hardware and harness facts.
+ */
+
+import type { FastifyInstance, FastifyReply, FastifyRequest } from 'fastify';
+import {
+  ApiErrorCode,
+  createErrorResponse,
+  type ApiResponse,
+  type HardwareFacts,
+  type HarnessFact,
+  type LocalModelCatalog,
+  type LocalModelStatus,
+  type Recommendation,
+} from '../../types.js';
+import { getLocalModelCatalog } from '../../config/local-model-catalog.js';
+import { readHardware } from '../../local-model/hardware.js';
+import { buildHarnessFacts } from '../../local-model/harness-facts.js';
+import { recommend } from '../../local-model/recommend.js';
+
+/** What the route calls. Each member defaults to the real module; a test overrides what it needs. */
+export interface LocalModelRouteDeps {
+  readHardware: () => Promise<HardwareFacts>;
+  getCatalog: () => LocalModelCatalog;
+  buildHarnessFacts: (catalog: LocalModelCatalog) => Promise<HarnessFact[]>;
+  recommend: (hw: HardwareFacts, catalog: LocalModelCatalog, harnessFacts: readonly HarnessFact[]) => Recommendation;
+}
+
+export const defaultLocalModelRouteDeps: LocalModelRouteDeps = {
+  readHardware: () => readHardware(),
+  getCatalog: getLocalModelCatalog,
+  buildHarnessFacts,
+  recommend,
+};
+
+export function registerLocalModelRoutes(app: FastifyInstance, deps: Partial<LocalModelRouteDeps> = {}): void {
+  const resolved: LocalModelRouteDeps = { ...defaultLocalModelRouteDeps, ...deps };
+  void resolved;
+  app.get(
+    '/api/local-model',
+    async (_req: FastifyRequest, reply: FastifyReply): Promise<ApiResponse<LocalModelStatus>> => {
+      reply.code(501);
+      return createErrorResponse(ApiErrorCode.OPERATION_FAILED, 'GET /api/local-model is not implemented yet');
+    }
+  );
+}
diff --git a/src/web/server.ts b/src/web/server.ts
index f9202601..67ee93a5 100644
--- a/src/web/server.ts
+++ b/src/web/server.ts
@@ -264,6 +264,7 @@ import {
   pruneIdleLlamaSwapLogTails,
   tryWebviewRefererFallback,
   registerCliRegistryRoutes,
+  registerLocalModelRoutes,
 } from './routes/index.js';
 import { isLostWebviewFrameNavigation } from './webview-proxy.js';
 import { CronService } from '../cron/cron-service.js';
@@ -1417,6 +1418,7 @@ export class WebServer extends EventEmitter {
     registerDoctorRoutes(this.app);
     registerCustomModelRoutes(this.app);
     registerCliRegistryRoutes(this.app);
+    registerLocalModelRoutes(this.app);
 
     // Cron: build the service from the same context, recompute
     // due times for any persisted jobs, then expose it to its routes.