deepseek-harness/packages/experimental/inspector/README.md

description, kind

description	kind
Experimental Chrome DevTools inspection for Host and browser Client Cordis runtimes, including Console evaluation, Sources, Network capture, Elements trees, and a CDP-independent query API.	package-reference

@deepseek-ai/dsh-experimental-inspector

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Summary

Use this experimental inspector to inspect one running dsh Host and its browser Clients in Chrome DevTools. It exposes Host and Client Console contexts, Host Sources and debugging, captured Host fetches, and a shared Cordis tree while keeping all CDP state in a Worker.

The package is private and excluded from releases. The Worker never accesses live Cordis objects: the shared Host/Client collector projects them into validated snapshots before transport. Cordis also owns plugin composition, ctx.inspector registration, bootstrap injection, and disposal.

Table of Contents

• Runtime layout
• Configuration
• Observation API
• Cordis tree inspection
• Host fetch capture
• Security
• Model Experience
• Known Limitations and Deferred Work
• Dev Note

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Runtime layout

The Host plugin starts the Worker and connects a dedicated MessagePort. The Client plugin reads the injected globalThis.__DSH_INSPECTOR__ bootstrap and opens a separate authenticated WebSocket directly to the Worker. Chrome DevTools connects to the Worker's CDP WebSocket. A private node:inspector.Session per DevTools connection attaches from the Worker to the Host main thread, so Host Console evaluation, Sources, breakpoints, and resume remain available while Host JavaScript is paused.

The source tree follows those execution environments: client/ and host/ provide mirrored adapter entry paths, worker/ contains only Worker-thread orchestration and Chrome protocol state, and shared/ contains environment-independent Cordis and network models, normalized realm backend interfaces, and the internal bridge protocol. Worker-side Client and Host adapters are mirrored under worker/realms/; a Client adapter in that directory still executes in the Worker.

Host and Client producers send internal observation records rather than CDP messages. Records contain a source generation, sequence, source-clock timestamp, topic, and JSON payload. The Worker validates every process or network frame, owns source state and retention, and translates recognized topics to standard CDP domains.

Client sources declare typed Runtime, Console, and read-only Sources capabilities. Runtime.enable publishes the real Host execution context and one synthetic context for every connected Client source. Selecting a Client context routes evaluation, property access, function calls, promise awaiting, and object release to that browser realm. Client Console arguments use the same session-local object table, while Debugger.enable publishes the built lib/client.js catalog and Debugger.getScriptSource reads bounded content chunks. Client-script breakpoints, step, and call frames remain unsupported; target-wide pause and resume control the Host debugger only.

Both plugin faces run the same browser-safe Cordis collector. It converts reachable Context and Fiber objects into a versioned CordisTreeSnapshot; the Worker stores that CDP-independent representation and projects each Host or Client source into the Elements panel.

Configuration

The Host plugin injects webServer and accepts these fields:

Field	Default	Meaning
host	127.0.0.1	Worker endpoint bind address; only loopback is accepted
port	9230	First Worker endpoint port; occupied ports advance upward, while 0 requests an OS-assigned port
clientOrigins	[]	Additional exact browser origins accepted by /ingest; loopback origins remain accepted
captureFetch	true	Wrap globalThis.fetch and publish every later call
maxRequestBodyBytes	8 MiB	Per-request captured request-body prefix
maxResponseBodyBytes	32 MiB	Per-request captured response-body prefix
maxBodyChunkBytes	48 KiB	Raw bytes carried by one body record before base64 encoding
maxJournalBytes	256 MiB	Worker-retained request and response body bytes
maxRetainedRequests	2000	Active and completed requests retained by the Worker
maxSourceFrameBytes	128 KiB	Encoded source-frame limit
maxSourceRecordsPerFrame	128	Records in one source batch
maxQueuedRecords	2048	Per-producer records waiting for transport
maxQueuedBytes	16 MiB	Per-producer queued encoded bytes
startupTimeoutMs	10 seconds	Worker readiness deadline
stopTimeoutMs	5 seconds	Graceful Worker shutdown deadline before termination
clientReconnectBaseMs	250 ms	First Client reconnect backoff cap
clientReconnectMaxMs	5 seconds	Maximum Client reconnect backoff cap
clientRuntimeTimeoutMs	30 seconds	Deadline for one Worker-to-Client Runtime or Sources command
queryTimeoutMs	10 seconds	Deadline for one non-CDP semantic query
maxClientRuntimeObjects	10000	Live Client object handles retained per DevTools connection
maxClientRuntimeProperties	2000	Property descriptors returned by one Client object inspection
maxClientSourceBytes	8 MiB	Maximum encoded bytes read from one Client script or source map
maxCordisNodes	2048	Context and Fiber nodes admitted from one realm snapshot before truncation
maxDisconnectedCordisTrees	8	Last disconnected realm trees retained as non-live snapshots

The generated configuration catalog is the exhaustive source for accepted fields and their declarations.

The Host logs a devtools:// URL after the Worker listens. The same Worker serves /json, /json/list, /json/version, the target WebSocket under /devtools/page/<id>, and the Client source at /ingest.

Observation API

Both plugin faces provide the same service:

import type { Context } from '@deepseek-ai/cordis'
import type { InspectorJsonValue } from '@deepseek-ai/dsh-experimental-inspector'

declare const ctx: Context
declare const topic: string
declare const jsonPayload: InspectorJsonValue

ctx.inspector.publish(topic, jsonPayload)
await ctx.inspector.cordis.getTree()

Publishing validates lossless JSON and schedules delivery without waiting for the Worker. Each source has a bounded queue. Overflow is reported as a sequence gap and never delays the observed application operation. cordis.getTree() reads the Worker's latest detached semantic snapshot without creating a CDP session or enabling Runtime, Debugger, or Sources.

Cordis tree inspection

The Elements document has fixed <host> and <clients> containers. <host> contains the Host root Context; <clients> contains one <client> per Client source, and each <client> contains that realm's root Context. The Cordis root Fiber is omitted. Every other Fiber is a child of fiber.parent, owns exactly one Context child for fiber.ctx, and carries only uid="<Cordis Fiber.uid>"; Context elements have no attributes. Context-only extend(), isolate(), and intercept() layers remain direct Context descendants.

Host and Client publish the same nested CordisTreeSnapshot type. Context and Fiber nodes carry opaque object handles for realm-local object lookup; Fiber nodes additionally carry Cordis uid. The Worker composes those realm snapshots into one { host, clients } inspection tree. It assigns BackendNodeId values per source generation; each DevTools connection assigns its own NodeId values; DOM.resolveNode asks the owning Host or Client Runtime for a connection-local RemoteObjectId. DOM.requestNode maps that object id back to the same Elements node. ctx.inspector.cordis.getTree() and DSHInspector.getCordisTree read the detached consumer-neutral tree without routing handles or CDP ids.

Sources publish complete snapshots, while the Worker compares stable backend node identities before notifying DevTools. Unchanged snapshots emit no DOM event; additions, removals, and attribute changes use node-level CDP events, and sibling reordering replaces only that parent's children. Existing NodeId values and unaffected Elements expansion remain stable.

When a Client disconnects, its Console execution context and live object ids are destroyed immediately. With disconnected-tree retention enabled, Elements keeps the last tree unchanged while connection state remains in the inspection model rather than becoming an unreviewed DOM attribute. Reconnection keeps the logical source id, creates a new synthetic CDP context id for the new transport generation, and replaces the stale tree after its complete snapshot arrives. The Worker retains at most maxDisconnectedCordisTrees such snapshots; zero removes them immediately.

Host fetch capture

Fetch capture is on by default and records the complete URL, all request and response headers, request body, response body, status, timing, errors, and cancellation. It does not redact credentials, cookies, query values, or payloads. Body capture reads clones; the caller receives the original Response as soon as the original fetch resolves.

The configured body limits bound retention rather than select fields: capture keeps the prefix and marks the result truncated. Network.getRequestPostData and Network.getResponseBody read the Worker's retained bytes. Network.streamResourceContent returns the buffered prefix and adds later response bytes to Network.dataReceived for that DevTools connection, which drives live Response and EventStream views. Direct Undici Client/Dispatcher calls and fetch references retained before plugin activation are outside this observer.

After response headers arrive, bytes captured before a caller-side abort remain available through Network.getResponseBody, while the request ends with Network.loadingFailed { canceled: true }. A fetch rejection before response headers follows the same canceled failure path.

Security

The CDP target grants arbitrary code execution in both Host and connected Client realms through Runtime.evaluate; Host Debugger operations provide additional control. Full fetch capture includes secrets. The Worker therefore accepts only a 127.0.0.1 bind address. Client ingest additionally requires a random WebSocket subprotocol token injected by the Host and rejects non-loopback origins unless explicitly configured. The CDP socket itself has no token; loopback binding is its only access control.

Model Experience

None, as this developer-only inspector observes runtime activity without changing model requests.

KV Cache effect

None; this package neither assembles nor sends a provider request.

Known Limitations and Deferred Work

• Client active debugging is unsupported — Console events, Runtime evaluation, RemoteObject access, and read-only lib/client.js Sources work. Client-script debugger requests return explicit unsupported errors; target-wide pause and resume control the Host only.
• Client Sources expose the Inspector bundle only — other page scripts are not cataloged by this package.
• Client evaluation uses page JavaScript — page Content Security Policy can block dynamic evaluation, and the synthetic context does not provide DevTools command-line helpers or native REPL declaration semantics.
• Fetch interception covers globalThis.fetch — direct Undici APIs and fetch references retained before activation are not observed.
• Body cloning has cost — full capture tees request and response streams up to the configured limits and can increase memory and I/O pressure. The retained-body limit does not include buffering inside the stream tee, including an oversized source chunk or data queued for a slower application reader.
• No automatic Worker restart — an unexpected Worker exit fails the current Inspector instance; lifecycle recovery belongs to a later change.

Dev Note

Working context for maintainers — click to expand

None.