qp-exa-dynamic

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An Exa-backed WebSearchProvider for the DeepSeek Harness ctx.web seam, with Exa Dynamic Highlights on by default and an /exa command that changes highlights, search type and result count at runtime.

dsh plugin --profile web add qp-exa-dynamic

Why this exists

The first-party @deepseek-ai/dsh-web-search-exa cannot reach Exa Dynamic Highlights, for two independent reasons:

1. Its request body is hardcoded. It sends contents.highlights.highlightsPerUrl, and no config field it accepts reaches a dynamic field.

2. Dynamic Highlights is a beta API and needs a header. Every request that sets dynamic: true must also send Exa-Beta: dynamic-highlights-2026-08-28. That provider's headers are authorization, content-type, accept and user-agent — no Exa-Beta. Without it Exa answers HTTP 400:

   {"error":"'highlights.dynamic' is in beta. Send the 'Exa-Beta: dynamic-highlights-2026-08-28' request header to use it.","tag":"INVALID_REQUEST"}
   

This provider sends both, and drops highlightsPerUrl entirely — measured against the live API, Exa ignores that parameter, returning byte-identical payloads for values 1 and 5. It uses maxCharacters instead, which is the knob that actually works when Dynamic Highlights are off.

Measured

Real /search calls, one query, 8 results:

Configuration	Highlight characters
First-party provider's default (no working knob)	51,152
This provider, dynamicHighlights: false + highlightsMaxCharacters: 1500	10,973
This provider, dynamicHighlights: true (default)	12,716

Dynamic Highlights is not a uniform truncation: it concatenates the retrieved documents into one input, runs a single forward pass, and allocates a shared budget across the result set — so useful pages keep more context and redundant ones get less.

Install

dsh plugin --profile web add qp-exa-dynamic

The package declares a dsh.bundle manifest, so its bundle patch inserts the provider row for you — no hand-written patch entry is needed.

To select it, override the web row in $DSH_HOME/profiles/web/cordis.patch.yml:

- id: web
  name: '@deepseek-ai/dsh-web'
  config:
    searchProvider: exa
    fetchProvider: http

A patch replaces the targeted row's whole config rather than merging into it, so fetchProvider: http must be restated or the fetch provider is dropped.

Then give it a key, either as plugin config:

- id: qp-exa-dynamic
  name: qp-exa-dynamic
  config:
    apiKey: 'your-exa-api-key'

or through the environment. apiKey is declared role('secret'), so it never appears in a describe() response — but a plain-text config file is still a plain-text config file; prefer the environment when you can.

On $DSH_HOME/.env. The plugin reads apiKeyEnv (default EXA_API_KEY) through the harness's launch-environment snapshot, which is documented to consult the inherited environment, the invoking directory's .env and the Harness home's .env. That worked in some deployments and not in others — on one Windows install the snapshot came back without the variable even though the file was correct, and the config apiKey above was the fix. If your provider reports registered but unavailable, the key is not reaching it; set apiKey directly.

Restart dsh web after changing the environment. cordis.patch.yml itself is hot-reloaded, so config edits apply without a restart.

Configuration

Every field has a safe default; you normally only supply a key.

Field	Default	Meaning
providerId	exa	Registry id. Change it only to coexist with another Exa provider.
apiKey	unset	Literal key; falls back to apiKeyEnv.
apiKeyEnv	EXA_API_KEY	Environment variable consulted when apiKey is unset.
baseURL	https://api.exa.ai	Exa endpoint; /search is appended.
searchType	auto	Retrieval type — see below. Runtime-settable with /exa type.
numResults	8	Source cap. Runtime-settable with /exa results.
dynamicHighlights	true	On by default; adds the required Exa-Beta header. Runtime-settable with /exa.
highlightsMaxCharacters	unset	Per-page highlight cap, used only when dynamicHighlights is false.

dynamicHighlights is never combined with highlightsMaxCharacters: Exa sizes and distributes the shared budget itself when dynamic is on, and its docs warn against combining the two.

The /exa command

Typed in the composer. It runs directly against the interface and creates no model message.

Command	Effect
/exa	Toggle Dynamic Highlights
/exa on / /exa off	Set them explicitly
/exa type	List the retrieval types
/exa type deep	Set the retrieval type
/exa results	Report the source cap
/exa results 3	Set the source cap
/exa status	Report every knob, the available types, and the real ceiling

Plain words, no punctuation: the command declares no argument hint, so the composer inserts no template to edit around. /exa status lists the retrieval types too, so "which types were there again" never costs a second command, and a mistyped argument replies with copy-pasteable examples.

Writes land in the qp-exa-dynamic settings namespace's user layer, so they survive a restart. Clearing that section returns the plugin to its configured defaults.

Measured on one provider instance, one query: switching Dynamic Highlights off took the same search from 12,716 to 57,958 highlight characters — a 4.6x difference, applied on the next search.

The exa_search tool

The plugin also registers a second, model-facing tool beside web_search:

exa_search(query: string, maxResults?: integer)   // maxResults 1-50

It exists because of a hard structural fact: ctx.web.search() caps its result at the caller's request.maxResults, and dsh-tool-web sends its own searchMaxResults on every call — so no provider can ever exceed that cap, and raising it means forking an agent preset. This tool owns its own request.maxResults, so the result count becomes a per-call model argument instead of a deployment-level ceiling.

That makes the preset fork optional. Two ways past the default 8 sources:

Want	Use	Needs the preset fork?
20 sources for one question	exa_search(query, maxResults: 20) — just ask in words	no
/exa results 20 to work	the /exa command	yes

/exa results is a fine setting to keep even without the fork, because it is what this tool falls back to: with /exa results 20 set, exa_search(query) with no maxResults returns 20. It is web_search alone that stays clamped to the deployment's ceiling.

The tool goes through ctx.web like web_search does, so it uses the same selected provider, the same search type and the same Dynamic Highlights setting; only the count differs. Its ceiling of 50 is its own — dynamic highlights measured ~1.6k characters per source, so 50 is already ~20k tokens of context.

A prompt section next to web_search's tells the model when to reach for it; ordinary lookups stay on web_search. If the composition has no tools registry the provider still mounts and only the tool is absent.

Retrieval types

Exa's type is the latency/quality dial. All eight were verified against the live API; measured latency for one query, 8 results:

Type	Measured	Use
keyword	464 ms	Keyword only, fastest
neural	737 ms	Semantic retrieval
fast	798 ms	Speed with minimal quality loss
instant	856 ms	Real-time (chat, voice)
auto	1,914 ms	Default
deep-lite	3,116 ms	Lightweight synthesized output
deep	5,282 ms	Multi-step reasoning
deep-reasoning	18,278 ms	Hardest research tasks

The first-party provider's schema lists only auto, keyword and neural — that set is stale. This provider exposes all eight.

The deep* types are discounted by this seam

Measured through this provider's own class, same query, dynamic highlights on:

Type	Time	Sources returned
fast	718 ms	8
auto	215 ms	8
deep	6,891 ms	3
deep-reasoning	14,776 ms	4

The raw API returns 8 results for deep; the rest carry no non-blank highlight and are dropped, because the seam has no other field to derive a snippet from and inventing one would make the seam lie. The deep* family's real product is the synthesized output, which WebSearchSource has no field for. In practice the useful range here is keyword, neural, fast, instant and auto.

Result count belongs to dsh-tool-web

Worth stating plainly, because it is easy to misread:

• The model-facing web_search tool takes only queries — the model cannot ask for a count.
• The ceiling belongs to dsh-tool-web: searchMaxResults, default 8. Its own comment: "The consumer owns the returned-context limit; providers and models do not."
• The tool sends maxResults on every call, and the seam truncates the returned sources to it — so no provider can exceed that ceiling.

That makes this plugin's numResults one-directional: it can pull the count down, never up.

Configured	Tool ceiling	Sent to Exa
3	8	3
12	8	8 (clamped)
20	8	8 (clamped)

/exa status and /exa results report the ceiling the provider actually observed, so a clamped value is explained rather than silently applied.

Raising the ceiling is not a profile-patch edit in the Web app. dsh-web-app disables the host tool-web row — - id: tool-web / disabled: true — because only the web service and its search provider are host-side; the model-facing tool is per session, and the one that actually runs comes from the agent preset. The shipped standard preset's row carries fetch and searchTimeoutMs and no searchMaxResults, so it takes the schema default of 8. A profile patch targeting tool-web lands on the disabled host row and does nothing at all.

Changing it therefore means forking the preset: copy standard into $DSH_HOME/.agent-presets/, add searchMaxResults to its tool-web row, and select it as the default. That is a real trade — a copy does not track upstream updates to the shipped preset, and the default is read when a session is created, so running sessions keep the preset they assembled with. For most uses leaving it at 8 is the better deal: /exa results still pulls the count down, which is the direction that saves tokens.

Known limitations

• Exa's beta surface can move. dynamic-highlights-2026-08-28 is a research preview; a change on Exa's side means updating DYNAMIC_BETA_VALUE.
• Results without highlights are dropped, matching the seam's rule. With dynamic highlights on, 8 of 8 results carried a highlight in testing, so it rarely fires.
• No category, domain or date filters, and no full text. Those are Exa features this provider does not expose yet.
• One of this and the first-party Exa provider per profile. Both register the provider id exa by default; running both needs a distinct providerId on one of them.
• Tested against dsh 0.1.5-rc.1 only, which is what the peer ranges pin.
• Without a settings service the /exa writes are in-memory only. The provider itself works either way; without a command registry there is simply no /exa.

Development

node test/index.test.js    # 40 unit tests, no API key needed
EXA_API_KEY=... node test/live.mjs   # hits the real API, spends credit

Run the test file directly rather than through node --test: the test runner spawns a child process per file with piped stdio, which fails with spawn EPERM in a restricted sandbox.

Uninstall

dsh plugin --profile web remove qp-exa-dynamic

Remove the web override from cordis.patch.yml to return to the built-in DeepSeek search. That edit is hot-reloaded, so it takes effect immediately.

License

MIT